PythonState: Add animation proxies support
- Add a TraceProxy method in smtrace.py
- Add animation proxies support with TraceAnimationProxy method
- Use TraceProxy in CreateAnimationTrack method
- Use new methods in smstate to support animation proxies in state
- Add tests
- Hide SaveExtracts coda in certains cases (see below)
Edited by Mathieu Westphal (Kitware)