WyC: added support for disambiguating tuple expressions from non-tuple expressions.
WyC: added support for disambiguating tuple expressions from non-tuple expressions.

hjwylde/whiley-compiler,Whiley/WhileyCompiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler