Animation performance

Improvements to caching

1. Caches are now maintained on the rendering side and not the data processing side. This avoids the need to re-deliver data when looping over animations even when caching is enabled.
2. Caching is handles by views, rather than representations, making it easier on representation developers.
3. All views support caching.
4. Data objects and Mtimes for data objects provided to the mapper are not changed unless the upstream pipeline changed even when using cache.
5. Representation pipelines not affected by the animation no longer re-update, thus avoid wasting cache space as well as time when playing animations.