"patchwise-crop" need a patch shape // channel notation inconsistencies

[Pfleiderer-Adrian]

In processing/preprocessor.py it says on the patch_shape value documentation: "This parameter will be redundant if fullimage or patchwise-crop analysis is selected!!". But in the init-function, the patch-shape parameter check fires an error if the patch-shape is None or not specified when patchwise-crop is selected as analysis option.

The documentation says also that the subfunction use the patch-shape in first-channel mode but the MIScnn I/O Definition uses the last-channel notation. Maybe this sould be unified?