swift234

Teach the parser to add the didSet/willSet functions to the enclosing
type, so we emit them.  Add mangler (and demangler) support for these.
Enhance our testcase to check to make sure that stores within these
specifiers are direct, they don't cause recursive infinite loops.

John, I picked w/W for the mangling letters, let me know if this is ok.


Swift SVN r13050