MakeSceneFiles() now separate from BatchRender(), working for MakeMaterialSphere.
New hints.isCachedConversion allows reuse of existing scene files, without invoking converters.
MakeSensorImages() can skip nonexistent data files.
Add pwd() to working path only in WriteMappedSceneFiles, not top-level MakeSceneFiles().

That way, the original scene file gets located before the copy in hints.tempFolder, when tempFolder is beneath pwd().
Merge branch 'convert-render-split' of github.com:DavidBrainard/RenderToolbox3 into convert-render-split
"isReuseSceneFiles" is a better hint name than "isCachedConversion".
MakeMaterialSphere should defer to global preference for isDryRun, etc.
TestAllExampleScenes() should defer to global preference when isDryRun is omitted.
MakeSceneFIles/makeSceneFIle() needs to use conditionNumber to make default file names.
Example Scenes all use MakeSceneFiles() in addition to BatchRender().
BatchRender() prints isParallel message before rendering.
MakeSceneFiles() tries to avoid copying a file onto itself, which is a Matlab error.
New top-level scripts for generating example scene files, and rendering them later.
Top-level scene file scripts save results for later review.
TestAllExampleScenes excludes figure-making functions.
debugging top-level example scene scripts
TestAllExampleScenes includes timing results
rename MakeAllExampleSceneFiles -> Generate- because Make is a special prefix
update comments for file rename
Example scenes with multiple Make* scripts provide distinct imageName conditions file variables.