Create VarianceChecker
Add VarianceChecker to TopDownAnalyzer
Add test (recursive resolve in property declaration) to JetPsiChecker
Added Variance tests
Fix blinking test
Fix protected visibility in class object.
Add receiver to Visibility#isVisible
Change usage "v == Visibilities.PRIVATE" to Visibilities.isPrivate(v)
Temporary hack for KT-6320
Buildserver auto merge