[Language Idea] Add pressed for binding keyboard events (#3483)

Makes it possible to test if a certain keyboard button is pressed.

**Description**
Fixes #3337, #3413, #3406 and #3546.

- Adds the **ifpressed** grammer rule, for level 5 and upwards
- Adds the **UsesPygame** Transformer
- Uses the PyGame library - #3335 

**How to test**
Open up level 5 and use the following snippet

```python
if x is pressed print 'Ouch!' else print 'Hi!'
```
This will map the keyboard press _x_ to print 'Ouch' and any other to 'Hi!'. You can change _x_ by any Latin letter or one digit number. 
After running the code, if you press _x_ it should output 'Ouch!'. The program should stop executing after the output.

![Hedy_—_Mozilla_Firefox_2022-10-25_11-50-32_AdobeExpress(1)](https://user-images.githubusercontent.com/48225550/197743506-64076374-8110-4ee8-ac9f-52eba1883388.gif)

Next, Open up level 8 and use the following snippet
```python
if a is pressed
    print 'Ouch!'
else
    print 'Hi!'
```
This is necessary because in level 8, inline if statements are not allowed anymore. The result should be the same as in level 5.

Try out some turtle commands as well!
```python
if x is pressed forward 50 else turn 90
```
It should get the turtle moving or turning.


**:exclamation: Important Comments**

- The keyword _pressed_ is currently not highlighted. Essentially pressed is a state (for kids: "a special variable") and not a command. I think it would be cool to give these "special variables" a different color (blue maybe?).

app.py

@@ -375,8 +375,13 @@ def parse():
                 exception = ex
         try:
             response['Code'] = transpile_result.code
+
+            if transpile_result.has_pygame:
+                response['has_pygame'] = True
+
             if transpile_result.has_turtle:
                 response['has_turtle'] = True
+
         except Exception as E:
             pass
         try:
@@ -1071,7 +1076,7 @@ def get_certificate_page(username):
     user = DATABASE.user_by_username(username)
     if not user:
         return utils.error_page(error=403, ui_message=gettext('user_inexistent'))
-    progress_data = DATABASE.progress_by_username(username)   
+    progress_data = DATABASE.progress_by_username(username)
     if progress_data is None:
         return utils.error_page(error=404, ui_message=gettext('no_certificate'))
     achievements = progress_data.get('achieved', None)
@@ -1083,11 +1088,11 @@ def get_certificate_page(username):
         count_programs = 0
     quiz_score = get_highest_quiz_score(username)
     longest_program = get_longest_program(username)
-    
+
     number_achievements = len(achievements)
     congrats_message = gettext('congrats_message').format(**{'username': username})
-    return render_template("certificate.html", count_programs=count_programs, quiz_score=quiz_score, 
-                            longest_program=longest_program, number_achievements=number_achievements, 
+    return render_template("certificate.html", count_programs=count_programs, quiz_score=quiz_score,
+                            longest_program=longest_program, number_achievements=number_achievements,
                             congrats_message=congrats_message)
 
 def get_highest_quiz_score(username):

content/keywords/en.yaml

@@ -51,4 +51,5 @@ length: length
 9: '9'
 0: '0'
 comma: ','
-quote: "'"
+quote: "'"
+pressed: pressed

content/keywords/nl.yaml

@@ -52,3 +52,4 @@ length: lengte
 0: '0'
 comma: ','
 quote: "'"
+pressed: ingedrukt

grammars/keywords-en.lark

@@ -40,3 +40,4 @@ _OR: _SPACE ("or" | "or") _SPACE
 _WHILE: ("while" | "while") _SPACE
 _LENGTH: "length" | "length"
 _COLOR : ("color" | "color") _SPACE?
+_PRESSED: ("pressed" | "pressed") _SPACE?

grammars/keywords-template.lark

@@ -40,3 +40,4 @@ _OR: _SPACE ({or} | "or") _SPACE
 _WHILE: ({while} | "while") _SPACE
 _LENGTH: {length} | "length"
 _COLOR : ({color} | "color") _SPACE?
+_PRESSED: ({pressed} | "pressed") _SPACE?

grammars/level1.lark

@@ -63,6 +63,7 @@ NAME: LETTER_OR_UNDERSCORE LETTER_OR_NUMERAL*
 
 LETTER_OR_UNDERSCORE: /[\p{Lu}\p{Ll}\p{Lt}\p{Lm}\p{Lo}\p{Nl}_]+/
 LETTER_OR_NUMERAL: LETTER_OR_UNDERSCORE | /[\p{Mn}\p{Mc}\p{Nd}\p{Pc}·]+/
+SMALL_LETTER_OR_NUMERAL: /[a-z]/ | /[0-9]/
 
 // Internal symbol added by the preprocess_blocks function to indicate the end of blocks
 _END_BLOCK: "end-block"

grammars/level17-Additions.lark

@@ -3,6 +3,9 @@
 command:+= ifs (elifs)* elses? -= ifs elses?
 // These will be handled by the preprocessor step in the merger
 // It will find the appropiate function for this anotation and modify it accordingly
+ifpressed_else<needs_colon>
+ifpressed<needs_colon>
+
 ifs<needs_colon>
 elses<needs_colon>
 elifs: _EOL _ELIF _conditions _COLON _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK

grammars/level5-Additions.lark

@@ -3,7 +3,7 @@ _empty_program: (_EOL | _SPACE)*
 _non_empty_program: _EOL* (command | error_invalid) _SPACE* (_EOL+ command _SPACE*)* _EOL* //lines may end on spaces and might be separated by many newlines
 
 //placing assign after print means print is will print 'is' and print is Felienne will print 'is Felienne'
-command:+= ifelse | ifs | list_access_var -= error_invalid | error_ask_no_quotes > assign
+command:+= ifpressed_else | ifpressed | ifelse | ifs | list_access_var -= error_invalid | error_ask_no_quotes > assign
 _if_less_command: print | ask | turtle | assign_list | add | remove | sleep | error_print_no_quotes | list_access_var | assign
 
 // error_invalid is moved from to command to program, so that command rules have priority over error_invalid
@@ -17,6 +17,9 @@ assign: var _IS textwithspaces
 error_print_no_quotes: _PRINT (textwithoutspaces | list_access | var_access) (_SPACE (textwithoutspaces | list_access | var_access))*  -> error_print_nq
 
 // new commands for level 5
+ifpressed_else: _IF SMALL_LETTER_OR_NUMERAL _IS _PRESSED _EOL* _if_less_command (_SPACE+ _EOL* | _SPACE* _EOL+) _ELSE (_SPACE+ _EOL* | _SPACE* _EOL+) _if_less_command
+ifpressed: _IF SMALL_LETTER_OR_NUMERAL _IS _PRESSED _EOL* _if_less_command
+
 _if_clause: _IF (condition (_SPACE+ _EOL* | _SPACE* _EOL+) | condition_spaces _SPACE* _EOL+ | error_condition) _if_less_command
 error_condition: condition_spaces _SPACE
 ifelse: _if_clause (_SPACE+ _EOL* | _SPACE* _EOL+) _ELSE (_SPACE+ _EOL* | _SPACE* _EOL+) _if_less_command
@@ -31,6 +34,7 @@ in_list_check: textwithoutspaces _IN var_access
 
 nospace: /[^\n, ]/
 
+
 textwithspaces: /(?:[^#\n،,， ]| (?!else|başka|अन्यथा|否则|senão|ellers|alie|иначе|altrimenti|annars|anders|ndryshe|inaczej|sinon|sonst|sino|אחרת|وإلا))+/ -> text //anything can be parsed except for a newline and a comma for list separators
 //a space is allowed, but it may not be followed by an else. The part " (?!else))" means space not followed by (negative look ahead) else
 //That is because allowing else in strings leads to issue #303
@@ -40,4 +44,3 @@ textwithoutspaces: /(?:[^#\n،,， *+\-\/eiиansbअ否אو]|א(?!חרת )|و(?!
 
 
 //
-

grammars/level6-Additions.lark

@@ -2,7 +2,7 @@ _print_argument: (_SPACE | quoted_text | list_access | expression | print_expres
 ?print_expression: var_access_print | error_unsupported_number | INT
 
 // redefining it entirely since it has many order-depending rules
-command: print | turtle | add | remove | sleep | error_print_no_quotes | ifelse | ifs | ask | list_access_var | assign | assign_list | error_invalid_space | error_text_no_print | empty_line
+command: print | turtle | add | remove | sleep | error_print_no_quotes | ifpressed_else | ifpressed | ifelse | ifs | ask | list_access_var | assign | assign_list | error_invalid_space | error_text_no_print | empty_line
 _if_less_command: print | turtle | add | remove | sleep | error_print_no_quotes | ask | list_access_var | assign | assign_list
 
 //splitting  these commands into two rules, one for equals and one for is so they can be properly handled in the translator

grammars/level8-Additions.lark

@@ -1,4 +1,4 @@
-command:+= ifs elses?
+command:+= ifpressed ifpressed_elses? | ifs elses?
 
 repeat: _REPEAT (INT | var_access) _TIMES _SPACE? _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK
 
@@ -7,8 +7,11 @@ repeat: _REPEAT (INT | var_access) _TIMES _SPACE? _EOL (_SPACE command) (_EOL _S
 condition: equality_check | in_list_check
 equality_check: (textwithoutspaces | NUMBER) (_IS | _EQUALS) (textwithoutspaces | NUMBER) (_SPACE | textwithoutspaces | NUMBER)*
 
-
+// from level 8 on ifpressed is implemented slightly differently
+ifpressed: _IF SMALL_LETTER_OR_NUMERAL _IS _PRESSED _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK
+ifpressed_else: _IF SMALL_LETTER_OR_NUMERAL _IS _PRESSED _EOL (_SPACE command) (_EOL _SPACE command)* _EOL (_SPACE)* _ELSE (_SPACE)* _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK
 // from level 8 on if is implemented slightly differently
+ifpressed_elses: elses
 elses: _EOL (_SPACE)* _ELSE (_SPACE)* _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK
 //'if' cannot be used in Python, hence the name of the rule is 'ifs'
 ifs: _IF condition _EOL (_SPACE command) (_EOL _SPACE command)* _EOL _END_BLOCK