Add German translation of control settings GUI buttons

[jonasholfelner]

No description provided.

[lunofe]

1. key.invtweaks_sort_inventory.desc: "Externes" is an adjective and should be lowercase as it describes the noun "Inventar"
2. key.invtweaks_sort_either.desc: "Unter" should be lowercase as it isn't a noun
3. key.invtweaks_sort_either.desc: I've never heard someone use the word "Mauspfeil" as a translation for "mouse pointer" or "cursor" before. "Mauszeiger" would definitely sound better.