Editor also seems to start, didn't test much further.
Only tested 32bit Windows, I fear the editor code isn't 64bit clean..
I hope I haven't broken anything elsewhere..
Sys_GetScanTable() and MapKey() are only used by the Windows backend
or the Windows-only tools.
Rename to Win_GetScanTable() and move MapKey() as Win_MapKey() to
win_input.cpp.