Use unicode symbol to indicate current language

[FestplattenSchnitzel]

With this change the language flag won't look pixelated any more on high-res devices or when zooming in, also we will save another file that needs to be transferred.

[FestplattenSchnitzel]

Please note the current implementation is simple but hacky and should be changed maybe.

[lukasjuhrich]

@FestplattenSchnitzel I strongly presume this isn't a draft anymore, so I'll just go ahead and click „Ready for review“ myself.