Rewrite most of the translation stuff to be cleaner.
Also fix a bug where in-game only menu items become enabled after selecting a language when we're in various NewUI menus.
Rename Config::ilanguage to Config::iLanguage for consistency with other Config variables.
Use consistent pointer names.
Remove unneeded lines.
Rename Config::languageIni to Config::sLanguageIni for consistency.
Merge pull request #3806 from thedax/win32UITranslation

Win32 UI: Rewrite most of the menu translation code to be cleaner and simpler.