Separate deinflections into their own dictionaries

[StefanVukovic99]

The de-de dict is huge because of deinflections and there should be an option to get the dict with just the definitions.
A user will often have at least a bi- and monolingual dict, e.g. de-en and de-de, and does not need the deinflections from both.

Potential problem:
If a user doesn't install any deinflection dictionaries it might lead to a bad experience.