data, ui: comment handling

* CodeView displays comments as atomic regions. They are either displayed as a whole or not at all. Do nothing halfway!
* added CommentHandler that handles comments detected by clang.
* stored CommentLocations in database.

src/lib/data/parser/ParserClient.h

@@ -145,6 +145,8 @@ public:
 		const ParseLocation& location, const NameHierarchy& macroNameHierarchy, const ParseLocation& scopeLocation) = 0;
 	virtual Id onMacroExpandParsed(
 		const ParseLocation& location, const NameHierarchy& macroNameHierarchy) = 0;
+
+	virtual Id onCommentParsed(const ParseLocation& location) = 0;
 };
 
 #endif // PARSER_CLIENT_H