Prohibit all modifiers for enum entries

 #KT-2679 Fixed
Minor, fix some warnings in DeclarationsChecker
Make 'when' on nullable enums exhaustive if 'null' entry is present

 #KT-2902 Fixed
Fix incorrect "senseless null in when" on nullable type
Prohibit type parameters for enum classes

 #KT-5696 Fixed
Minor, don't call Type.getObjectType on array
Prohibit 'override' on classes and all modality on objects

 #KT-3464 Fixed
Don't output trailing spaces in Printer

Also don't output trailing empty lines in TestGenerator
Reorder imports in test generator

To make IDEA's Optimize Imports action a no-op on most of the generated tests
Regenerate tests

After recent changes to Printer and TestGenerator
Regenerate injectors and keyword strings

After recent changes to Printer
Regenerate .txt testData

Add newline to EOF, trim trailing spaces