Fix a bug where doc/generate_mdb_doc was putting the documentation for

Estimated hours taken: 0.5

Fix a bug where doc/generate_mdb_doc was putting the documentation for
the interactive query commands in the category "interactive" whereas
doc/mdb_categories was expecting this category to be called "queries".

util/info_to_mdb.c:
	Print error messages to stderr rather than stdout.
	Document the first argument as being a category name
	(the name of an mdb help category) rather than a section name.

doc/generate_mdb_doc:
	Avoid the assumption that the category name is the same as the
	section name; that is still the default, but it now sets the
	category for the "interactive" section to "queries".
	Invoke info_to_mdb with the category name rather than the
	section name.

trace/mercury_trace_internal.c:
	Update the category names in the pseudo-automatically-generated
	command list to reflect the above change.
	(Also improve an error message slightly.)

doc/generate_mdb_doc

@@ -18,6 +18,10 @@ debug_cmd_path="debug debugger"
 for section in interactive forward backward browsing breakpoint \
 	parameter help exp developer misc 
 do
+	case $section in
+		interactive)	category=queries ;;
+		*)		category=$section ;;
+	esac
 	info -f ./mercury_user_guide.info -o $tmp $debug_cmd_path $section
-	../util/info_to_mdb $section $tmp >> mdb_doc
+	../util/info_to_mdb $category $tmp >> mdb_doc
 done

trace/mercury_trace_internal.c

@@ -1122,7 +1122,7 @@ MR_trace_handle_cmd(char **words, int word_count, MR_Trace_Cmd_Info *cmd,
 				}
 			} else {
 				fprintf(MR_mdb_out,
-					"%s is not a valid command.\n",
+					"`%s' is not a valid command.\n",
 					words[2]);
 			}
 		}
@@ -2455,9 +2455,9 @@ static	MR_trace_cmd_cat_item MR_trace_valid_command_list[] =
 	** experimental commands.
 	*/
 
-	{ "interactive", "query" },
-	{ "interactive", "cc_query" },
-	{ "interactive", "io_query" },
+	{ "queries", "query" },
+	{ "queries", "cc_query" },
+	{ "queries", "io_query" },
 	{ "forward", "step" },
 	{ "forward", "goto" },
 	{ "forward", "finish" },

util/info_to_mdb.c

@@ -37,6 +37,8 @@ static	void	put_line_back(char *line);
 int
 main(int argc, char **argv)
 {
+	char	*filename;
+	char	*category;	/* mdb help category */
 	FILE	*infp;
 	char	*line;
 	char	command[MAXLINELEN];
@@ -47,12 +49,15 @@ main(int argc, char **argv)
 	bool	next_concept;
 
 	if (argc != 3) {
-		printf("usage: info_to_mdb section_name section_info_file\n");
+		fprintf(stderr,
+			"usage: info_to_mdb category_name section_info_file\n");
 		exit(EXIT_FAILURE);
 	}
+	category = argv[1];
+	filename = argv[2];
 
-	if ((infp = fopen(argv[2], "r")) == NULL) {
-		printf("cannot read %s\n", argv[2]);
+	if ((infp = fopen(filename, "r")) == NULL) {
+		fprintf(stderr, "cannot read `%s'\n", filename);
 		exit(EXIT_FAILURE);
 	}
 
@@ -81,7 +86,7 @@ main(int argc, char **argv)
 		}
 
 		slot += 100;
-		printf("document %s %d ", argv[1], slot);
+		printf("document %s %d ", category, slot);
 		if (is_concept) {
 			for (i = 0; line[i] != '\n'; i++) {
 				command[i] = concept_char(line[i]);
@@ -227,7 +232,7 @@ static void
 put_line_back(char *line)
 {
 	if (putback_line != NULL) {
-		printf("trying to put back more than one line\n");
+		fprintf(stderr, "trying to put back more than one line\n");
 		exit(EXIT_FAILURE);
 	}