Use r-prefix when necessary

Avoid pylint reports such as:

> W1401: Anomalous backslash in string: '\['. String constant might be missing an r prefix. (anomalous-backslash-in-string)

setup.py

@@ -5,7 +5,7 @@
 DEFAULT_BRANCH = "2.x"
 BASE_GITHUB_URL = "https://github.com/vit-project/vit/blob"
 
-MARKUP_LINK_REGEX = "\[([^]]+)\]\(([\w]+\.md)\)"
+MARKUP_LINK_REGEX = r"\[([^]]+)\]\(([\w]+\.md)\)"
 FILE_DIR = path.dirname(path.abspath(path.realpath(__file__)))
 
 with open(path.join(FILE_DIR, 'README.md')) as f:

vit/application.py

@@ -216,7 +216,7 @@ def register_managed_actions(self):
     def default_keybinding_replacements(self):
         import json
         from datetime import datetime
-        task_replacement_match = re.compile("^TASK_(\w+)$")
+        task_replacement_match = re.compile(r"^TASK_(\w+)$")
         def _task_attribute_match(variable):
             matches = re.match(task_replacement_match, variable)
             if matches:

vit/color.py

@@ -28,7 +28,7 @@ def __init__(self, config, task_config, theme, theme_alt_backgrounds):
         # without pipes, the 'color' config setting in Taskwarrior is not used, and
         # instead a custom setting is used.
         self.color_enabled = self.config.get('color', 'enabled')
-        self.display_attrs_available, self.display_attrs = self.convert_color_config(self.task_config.filter_to_dict('^color\.'))
+        self.display_attrs_available, self.display_attrs = self.convert_color_config(self.task_config.filter_to_dict(r'^color\.'))
         self.project_display_attrs = self.get_project_display_attrs()
         if self.include_subprojects:
             self.add_project_children()

vit/config_parser.py

@@ -18,9 +18,9 @@
 SORT_ORDER_CHARACTERS = ['+', '-']
 SORT_COLLATE_CHARACTERS = ['/']
 VIT_CONFIG_FILE = 'config.ini'
-FILTER_EXCLUSION_REGEX = re.compile('^limit:')
-FILTER_PARENS_REGEX = re.compile('([\(\)])')
-CONFIG_BOOLEAN_TRUE_REGEX = re.compile('1|yes|true', re.IGNORECASE)
+FILTER_EXCLUSION_REGEX = re.compile(r'^limit:')
+FILTER_PARENS_REGEX = re.compile(r'([\(\)])')
+CONFIG_BOOLEAN_TRUE_REGEX = re.compile(r'1|yes|true', re.IGNORECASE)
 # TaskParser expects clean hierarchies in the Taskwarrior dotted config names.
 # However, this is occasionally violated, with a leaf ending in both a string
 # value and another branch. The below list contains the config values that
@@ -294,7 +294,7 @@ def filter(self, matcher_regex):
     def subtree(self, matcher, walk_subtree=True):
         matcher_regex = matcher
         if walk_subtree:
-            matcher_regex = r'%s' % (('^%s' % matcher).replace('.', '\.'))
+            matcher_regex = r'%s' % (('^%s' % matcher).replace(r'.', r'\.'))
         full_tree = {}
         lines = self.filter(matcher_regex)
         for (hierarchy, value) in lines: