Checked that KT-4453 has been fixed recently by change in TipsManager
Completion: do not bold top-level functions
Completion: corrected presentation for extension properties
Completion: bold immediate members for extensions too
Removed code which does not seem to be needed at all
Added tests
Moved method checkIsExtensionCallable from ExpressionTypingUtils to TipsManager (converting it to Kottlin)
Moved methods for checking extensions applicability from TipsManager to extensionUtils.kt (and made them all extension methods)
Renamed TipsManager
Made ReferenceVariantsHelper class instead of object making method signatures shorter
Minor code refactorings
JS backend: test for KT-6277
JS backend: fix KT-6277 kotlinc-js: IllegalArgumentException when -output is a file name without directory prefix

#KT-6277 Fixed
Store refactoring

 #KT-1213 Fixed
Prefix inc refactoring
Get rid of store
Rewrite local var increment optimization
Fix for KT-4206: NoSuchFieldError with class objects

  #KT-4206 Fixed
Lazy receiver generation
Added thiz constant in StackValue, some refactorings