Import 9735c4a3ed: Custom shader fallback into PBR fixes, ignores normal maps to stop flickering, removed cruft (by Caitlyn)

This is an automated proposal to look at a commit made by Caitlyn and import it into Overte

Commit:	9735c4a3ede24f4020c1d19e896e91b990ef8fd3
Author:	Caitlyn
Date:	Sat, 11 Apr 2020 23:42

Custom shader fallback into PBR fixes, ignores normal maps to stop flickering, removed cruft

Stats:

Filename	Stats	Lines	Added	Removed	Lines in blame
libraries/entities-renderer/src/RenderableMaterialEntityItem.cpp		15	8	7	⚠ 0
libraries/entities-renderer/src/RenderableShapeEntityItem.cpp		13	11	2	1
libraries/material-networking/src/material-networking/TextureCache.cpp		1	1	0	1
libraries/material-networking/src/material-networking/TextureCache.h		3	3	0	3
libraries/procedural/src/procedural/Procedural.cpp		11	0	11	⚠ 0
libraries/procedural/src/procedural/ProceduralSkybox.cpp		3	1	2	⚠ 0
libraries/render-utils/src/MeshPartPayload.cpp		2	0	2	⚠ 0
7 files	-	48	24	24	5

To work on this, please assign the issue to yourself, then look at the commit and decide whether this would be a good addition to Overte.

If the commit is useful, tag it with "Tivoli: Keep", and keep it open until it's merged.
If the commit is not useful, tag it with "Tivoli: Discard", and close it.
If the commit is not useful right now, but might be later, tag it with "Tivoli: Maybe later", and close it.
If it's hard to decide, tag it with "Tivoli: Discuss", and keep it open.

Useful commits should be submitted as a PR against Overte. Tag this issue in PR, so that it's automatically closed once the PR is merged.

You can cherry-pick this issue with this command:

git cherry-pick 9735c4a3ede24f4020c1d19e896e91b990ef8fd3

overte-org / tivolicloud