WIP: shared resource cache for FMG
ShaderGen: update to optimize geodes whose Geometry all shares the same state; ResourceCache share in session; API updates.
Merge branch 'master' into post-2.5
Adjusted saturation on building texture set
Add VirtualProgram ShaderComp::LOCATION_FRAGMENT_OUTPUT so you can customize the fragment emitter for MRT
Merge branch 'master' of github.com:gwaldron/osgearth