Fix deprecation and add further variables

Add support for additional variables

Add config file as a definit entrypoint to change existing variables
Add english UPB logo
Clean up file structure (move some files from root to misc)
Add UPB colors and remove codesnippets for RUB CorpID
Clean up existing files (unify whitespaces, etc)
Move background on titlepage to remove white stripe on lower left side

Fix deprecation warnings and errors

see https://komascript.de/faq_scrpage2_en regarding scrpage2.
On Arch Linux the template was no longer compilable, due to the deprecation. It might still work on Debian etc but should not break there (hopefully) as the replacement package exists since 2012.