We haven't fully updated references to union cases, and enums still are not
their own thing yet, but "oneof" is gone. Long live "union"!
Swift SVN r6783
-Introduce PersistentParserState to represent state persistent among multiple parsing passes.
The advantage is that PersistentParserState is independent of a particular Parser or Lexer object.
-Use PersistentParserState to keep information about delayed function body parsing and eliminate parser-specific
state from the AST (ParserTokenRange).
-Introduce DelayedParsingCallbacks to abstract out of the parser the logic about which functions should be delayed
or skipped.
Many thanks to Dmitri for his valuable feedback!
Swift SVN r6580
just move the Sema code into the Parser library. There is no way to use one without
the other. The library formerly known as Sema will get renamed.
Swift SVN r542
