Remove materials that are being moved to a plugin.
Fix test.
Update CHANGES.md.
Remove more instances of removed materials.
Update Sandcastle example images.
More robust computation of tile edge planes.
Temporarily disable horizon culling.

It's not working correctly for the root tiles in Canary.
Merge branch 'master' into remove-materials
Merge pull request #1382 from AnalyticalGraphicsInc/remove-materials

Remove materials
Fix and re-enable horizon culling.
Clean up plane computation.
Update CHANGES.md.
Merge remote-tracking branch 'origin/master' into tilePlanes

Conflicts:
	CHANGES.md
Merge pull request #1387 from AnalyticalGraphicsInc/tilePlanes

Fix tile plane and horizon culling problems in Chrome Canary
Merge branch 'master' into canary-failures