This allows us to map the keys which are not considered in
irrlicht's EKEY_CODE system, such as \, [, /, ] etc.

Constify keycode and move the static array of localizable names from the
guiKeyChangeMenu header to the implementation file, changing its name.

configwriting/saving isn't complete and will break your config if you use fancy keys

configwriting/saving isn't complete and will break your config if you use fancy keys