more conversion sources, not just mixamo

[enziop]

has to be checked how root motion is done in different animation databases
then maybe implement preset dropdown for different sources

[brandiqa]

Just a thought, you can separate the bones mapping data from the source code and place it in a data file like a JSON file. Quick question, can the following bones be remapped automatically?

- lowerarm_twist_01_l -> hand_l
- upperarm_twist_01_l -> upperarm_l
- lowerarm_twist_01_r -> hand_r
- upperarm_twist_01_r -> upperarm_r
- thigh_twist_01_l -> thigh_l
- calf_twist01_l -> None
- thigh_twist_01_r -> thigh_r
- calf_twist01_r -> None