remove uneeded "extern HWND hWndMainWindow;" declaration
fix link error with i686-w64-mingw32 4.6.3 on linux box:
   regression commit : aa9528fcf4f38988008e955e413edf512d080ece
Move LKLanguage.cpp public prototype to LKLanguage.h
Replace Win32 "HPEN" type by new portable class "LKPen"