Revert "[functions.expression] add possibility to create() with non-empty gradient"
Revert "[functions.expression] add possibility to create() with non-empty gradient"

This reverts commit 23835015adb4ec41f3423a37e27f9ff43aebda38.

renemilk/DUNE-Stuff,renemilk/DUNE-Stuff,renemilk/DUNE-Stuff