[issue-3][issue-4][grammar] Minor bugfixes concerning comments and rdf:type shorthand a

+ rdf:type shorthand a isn't properly recognized inside bnode literal
   see: https://github.com/peta/turtle.tmbundle/issues/3
+ Comments not properly recognized in all contexts
   see: https://github.com/peta/turtle.tmbundle/issues/4
[autocomplete][ui] Renamed item icons and add one for Properties
[autocomplete] Supply image names for list items

+ Supply image names for list items
+ Change code involving access to previously global Constants/Functions
Add support for list item icons and move all global constants/funtions into Turtle module

+ Add support for list item icons (explicitly load them)
+ Move all global constants/funtions into Turtle module
+ Change how methods resource(id) and resources() retrieve their
elements