Continue local exception refactoring in C++

[bernardnormier]

This PR continues the local exception refactoring in C++.

In particular:

• all local exceptions now derive from Ice::LocalException
• the base class Ice::LocalException is now concrete and in its own header (LocalException.h)
  • concrete allows us to throw directly a LocalException instead of defining a new exception
  • this PR replaces CtrlCHandlerException by a plain LocalException with a message
• all the *ParseException are now a single ParseException
  • note that IceGrid defines its own ParseException user exception
  • this also shows it's a pain to add/remove/change local exceptions as all the derived mappings need to be updated