wxMenu_AppendRadioItem duplicated in kwxFFI.lib (multiply defined symbol)

[Randalphwa]

After the fix for issue #32, \wxMenu_AppendRadioItem\ is now defined in two places:

• \wx_menu.cpp\ (newly added by Fortran backend: naming issues and missing bindings #32 fix)
• \kwx_extra.cpp\ (where it was previously as a manual addition)

This causes a linker error in any project that links \kwxFFI.lib:

\
kwxFFI.lib(wx_menu.cpp.obj) : error LNK2005: wxMenu_AppendRadioItem already defined in kwxFFI.lib(kwx_extra.cpp.obj)
fatal error LNK1169: one or more multiply defined symbols found
\\

Fix: Remove \wxMenu_AppendRadioItem\ from \kwx_extra.cpp\ since it is now properly generated.