Multi Language Support

stl Multi-Language Support (currently with these languages).

At least the default language file (english) needs to be found, else stl will exit with an error. stl searches both in the Systemwide Configuration and in the User Configuration for language files, where those in the latter have a higher priority (so copying a system wide file to improve it is possible)

Every language found can be selected from the Language Dropdown Menu in the GUI Options. (a change requires a restart to take effect).

To give also the option to get a translated description in freshly created stl configfiles it is also possible to define an available language or an absolute path to a valid language file with the lang= Command Line option.

When no language file was found as a last resort stl will download its own projectpage and use the language file from there.

(every language file simply consists of multiple variables defining a text, so to contribute a translation, simply duplicate one of the existing ones and translate all variables inside)