Blender script to help with rig issues (unnatural joint positions, especially hands/wrists)

https://github.com/OrganicMonkeyMotion/mixamo-rig-joint-constraint

Basically, I have a character (a monkey) that while bipedal is not of human proportions, so I see many issues with joint rotations etc that are a nuisance to fix using the mocap based keyframes (the're so dense).  Some of that over rotation leads to body part "collisions" that, as it turned out, seem mostly addressed by simply constraining the joint rotations to "natural" limits. 

It occured to me that the problem was likely the way mixamo transferred (probably verbatum) joint rotations from the human proportioned source to the user targets.  Not a criticism, but with some bone constraints applied, many of the issues seemed to disappear.

So, I've simply used anthropometric data for humans, given the source in the mixamo site is a human biped.

There may already be a way to do this, but I am also using this as an excuse to learn blender add-on development etc.