Move IDVR to non-free
Description
Importance-driven volume rendering become too critical to keep it on sight. Actually that's an error since the beginning. We must move it to non-free asap.
Proposal
- Move ImportanceDrivenVolumeRenderer to a new bundle in nonfree
- Move as many shaders and materials as we can. The main ray-tracing shader might be tough to split. We may keep it as it is for now.
- Remove IDVR features from OgreViewer.
- Make a new app dedicated for the IDVR.