Refactor basic ReferenceResolver into CommonLookupSearch.
Refactor AbstractSemanticContext into Lang-Engine.
Refactor import code out of ReferenceResolver.
Refactor and changes to lexical lookup code, moved it to node class.
Tests and changes for Module top level synthetic named element.
minor cleanup.
Rename scope element interface.
ScopeLookup: changed searchScopes into a hashset.
Lang: added ChainedIterable.
Refactor INonScopedContainer method. Refactor CommonScopeLookup.