Removed green color for variable as function.

 #KT-3296 in progress
Added separate highlighting keys for variables invoked as function and function-like.
Removed commented out code from color settings.

When we implement actual highlighting for KDoc highlighting, returning these lines would be easy.
Refactored JetHighlightingColors to IDEA 12.1+ colors API.
Removed leading "/" to avoid tests failing.
Removed tooltip for variable as function(-like) call.