[FIX] rolling fix

customRoller is now a simple wrapper around rolling as a class.

to simplify, the custom step and mask keywords are not supported anymore, only forward and expand still exist.

i went this way because the otherwise the maintenance will come up again and again and eats up a lot of development time.

the test-suite also is deprecated because we just use pandas' rolling, and for forward facing windows, the common obj[::-1].rolling(..).function(..)[::-1]-hack

with this MR we need pandas>=3.0.0 !

closes #214 (closed) closes #146 (closed) closes #133 (closed)