* generator/MethodBody.cs : remove an unused var.
* generator/ReturnValue.cs : privatize a couple props. Refactor the
SymbolTable lookup logic to be generatable based.
svn path=/trunk/gtk-sharp/; revision=41528
* generator/ReturnValue.cs : use ToNativeReturnType for ToNativeType
instead of MarshalType.
* generator/Signal.cs : deal with boxed return values. beef up return
handling in the default handler generation code.
* generator/SignalHandler.cs : use ToNative return types for native
callbacks. Remove redundant casting/conversion in callback impl.
[Fixes#71899]
svn path=/trunk/gtk-sharp/; revision=39724
