Animation control system

[grillo-delmal]

This PR implements the feature described in #37. The main idea is to enable a system to use puppet animations in inochi-session, either by manual interaction with the UI, or by triggering them using external tracking parameters.

In this video I show how they can be triggered by a keyboard combination using puppetstring and by head motion.

session-animation-demo.webm

Here is the list of the implemented features:

• Play/Pause/Stop animations
• Loop control
• Trigger by tracking
  • Set custom trigger values
  • Control trigger value direction
• Save/Load animation control config in puppet

Some other things that I thought of that could get implemented too further along the line

• Trigger by event system
  • Event Queue
  • Implement tracking disconnected/reconnected as Event
  • Move tracking_lost animation to this system.
• Animation weight
  • Use additive and weight parameters.
  • Evaluate weighed fadein - fadeout options.

I'm still not sure if I want to implement the "Trigger by event" feature considering that currently the only application events I can imagine are "tracking lost" and "reconnect tracking", and those events are already being handled by setting a "tracking_lost" animation.

Its lots of code, so I would appreciate feedback on this feature :)