DescriptorRenderer: fix rendering of functional types in receivers
Test function types in decompiler
Approximating flexible types in decompiled text
Minor: JetPsiUtil#getElementTextWithContext() accepts PsiElement
Decompiler tests: check decompiled text was parsed correctly
Convert and rename JetClsStubBuilder
Rename and restructure plugin.libraries package

Rename: libraries -> decompiler
New subpackages: textBuilder, navigation
Rename test data folder: libraries -> decompiler
Rename stub classes: PsiJet*Stub(Impl) -> Kotlin*Stub(Impl)
Do logging with system dependent paths
Do the check with converted line separators
Comments binding (not complete yet)
Fixing declaration ranges in decompiled code - comment "/* compiled code */" now is inside property
Fixing taking doc-comment for declaration
Fixed doc-comment not attached to the first declaration with no package directive + incorrect placement of comments for enum entry
Fixed tests for variable/function extraction
Fixed tests for moving code up/down
Corrected comments binding so that comments before local functions and classes are bound to them
Simplified declaration's up/down mover because it does not need to attach comments to declaration manually anymore
Fixed diagnostics tests