Clarify usage of "scene file"

[benjamin-heasly]

RenderToolbox3 documentation and example code should use the phrase "scene file" more consistently.

It should use "Collada file" to refer to original Collada files from the 3D modeler. It should use "scene file" to refer to renderer-native scene files.

This will clarify examples that currently use a Collada "sceneFile" and a cell array of renderer-native "sceneFiles".

[DavidBrainard]

More generally, take an editing pass through the documentation and example code, and make the usage consistent with that we have developed in the paper. parent scene renderer-native scene files executive script rendering family (or something like that) recipe conditions file mappings file

[benjamin-heasly]

In c40eacc9a7bfd9209613c1a1f6fd8ab75c4890c7, I reviewed and updated all the doxygen comments and example executive functions for this usage.

[benjamin-heasly]

I also reviewed and updated all of the wiki pages here at GitHub.