20130125

- Gradient backdrop toggle and color overrides added to scene master.
- Caustics toggle added to light override.
- Radiosity flag support added to the native renderer scene master
override and scene master override UI.
- Tweaked override item display filter code to screen out items not
assigned to the current pass.
- Hoped for FiberFX workflow not available. FiberFX won't permit
breakouts for different elements - it fails if any of its settings
reference an element not present in the scene file. Note added to
documentation.
 - Planned to add passname to the FiberFX output name automatically.
Given the workflow limitation, it may not make sense at this time.
- FiberFX function called when no scene override in existence. Fixed.
- Enabled new feature for testing. Passed all tests in QA.
- Various tweaks internally regarding reqpost() actions to reduce
activity if the user does nothing at all.