use passed in lighting, and fix zoom/pan, in simple ray tracing renderer.
Merge pull request #15 from jameskress/master

Added eavlXGCParticleImporter
adding sphere primitives and basic bounding sphere acceleration to simple raytracer.
Merge branch 'master' of github.com:jsmeredith/EAVL
Added eavlXGCRestartImporter capabilities.
Acutally added the files...
Added check to eavlXGCParticlImporter GetFieldList to only return fields associated with current mesh.
Merge pull request #16 from jameskress/master

Added check to eavlXGCParticlImporter GetFieldList to only return fields associated with current mesh.
Merge remote-tracking branch 'origin/master' into rayTracer
Fixed intersection Depth.