Fix: DMC ProMP environments were actually all using DMP.

[D-o-d-o-x]

In fancy_gym/dmc/__init__.py all MP versions of DMP environments are registered to gym. The mp-configs are derived from default configs. All ProMP versions wrongfully derive from the DMP default-config instead of the ProMP default-config.
Since this config also contains the information as to which kind of MP to use, this leads to all ProMP environments using DMPs instead.

import fancy_gym
env = fancy_gym.make('dmc_ball_in_cup-catch_promp-v0', seed=1)
bb = env.env.env
print(bb.traj_gen.__class__)
-> <class 'mp_pytorch.mp.dmp.DMP'>   # should be ProMP, not DMP

[D-o-d-o-x]

The issue was already addressed by PR#75.