Tidied up language initialisation code.
Updated translation template file, added catalogs from wxWidgets 2.9.5.
Added translation files for Spanish, Russian and Chinese.

The translation files are from BOSSv2, updated using the BOSSv3
template. The Spanish translation file has had all its fuzzy matches
checked, but the others have not.

I think I need to go back and make sure that I don't have any trailing
spaces in the translatable text...