RadianceTest writes spectrum files to example folder, not pwd().
Collada scene converters return file name and scene documents.

This is useful for querying particulars of the scene, even after rendering.
BatchRender() applies conversions from raw outputs to radiance units.
New BatchRenderer/ functions to compute and apply renderer-specific scale factors for radiance units.
Merge branch 'master' of github.com:DavidBrainard/RenderToolbox3
New functions to scale renderer outputs into physical radiance units.

InitializeRenderToolbox() defines setpref() values to hold scale factors.
ComputeRadiometricScaleFactors() uses RadianceTest and first principles to compute a scale factor for each renderer.  Stores them with setpref().
MitsubaDataToRadiance() and PBRTDataToRadiance() apply the scale factor to renderer data.
BatchRender() invokes *ToRadiance functions automatically.