CORBA24 — special-casing TypeCode is unnecessary

The resolution to issue 3048 special-cases TypeCode in a manner that
essentially makes it a keyword. First of all, given that TypeCode lives in
the CORBA module, and thus is properly named CORBA::TypeCode, this is
highly irregular because it means we have a scoped keyword. Second, this
change also significantly breaks working products – it adopts
implementation details of certain compilers and rules out already-working
implementation approaches of other existing compilers. The OMG is not
supposed to dictate implementation. Finally, the rationale for the changes
made for 3048 centered around unquantifiable performance issues that IMO
affect only a very small minority of applications.

Incorporate changes and close issue.