[CHANGE] SyntaxDefinition - moved attributes foldable and type to the state tag;
[CHANGE] RegexSymbols - added documentation for show-in-comments - type of the state has to be set to comment, otherwise symbol recognition does not realise that a comment is a comment;
[CHANGE] RegexSymbols, SyntaxDefinition - added in-document links;
[CHANGE] added the Symbol Popup to the style guide;
[CHANGE] unified attribute declaration;
[CHANGE] SyntaxDefinition - added documentation for state attribute type: url;
[CHANGE] SyntaxDefinition - added documentation for state attribute containerState;
Merge branch 'feature/docu_clarifications' into develop