that fixes invocation:

>>> StringBuilder.length()

that was compiled to

>>> invokevirtual CharSequence.length()

and now compiles to

>>> invokevirtual StringBuilder.length()

Essentially patch rewrites FunctionDescriptor.containingDeclaration
when FunctionDescriptor is copied to subclass scope.

FunctionDescriptor now has kind field that can be
* DECLARATION (for "real" function, maybe abstract)
* DELEGATION
* FAKE_OVERRIDE (created for functions from supertypes)

All tests pass although some parts of code are buggy and ugly.

Random comments about this patch:

* FunctionDescriptor.overrides point to function descriptors of supertype scopes

* Filling of memberScope with supertypes is moved to OverrideResolver

* ExpressionCodegen.intermediateValueForProperty must be rewritten

* Patch adds not nice REDECLARATION reports (see compiler/testData/diagnostics/tests/*).
  Will be fixed later.