Brought some hardcoded strings to be constants. Fixed the prefix for language IDs. New functions: SetDefaultLanguage and GetDefaultLangauge. Changed ACR_LangAbbToLangID to ACR_LanguageAbbreviationToFullName. Added prototypes for ACR_LangIDToString and ACR_LanguageAbbreviationToFullName.
Changed some language operations to use the new functions/constants.