Add a new grid material, my first attempt at a Cesium Material.
Add new grid material to Materials demo in Sandcastle.
Update some wording.
Make Ellipsoids double-sided.
Messing with ellipsoid distances.
Pull out the main computation into a function that can be called twice.

Also fixed an issue with the final alpha value.
Stole some code from this Virtual Globe book I found laying around on @bagnell's desk.

Also commented out picking in the Volume demo because its bugs are driving me completely insane.
Merge pull request #603 from AnalyticalGraphicsInc/double-sided-ellipsoid

Make Ellipsoids double-sided.
Merge remote-tracking branch 'origin/master' into grid-material
Update default thickness.
Merge branch 'grid-material' into ed-test-ellipsoid-dist

Conflicts:
	Apps/Sandcastle/gallery/Volumes.html
	Source/Shaders/EllipsoidFS.glsl
Work in progress
Make grid lines and other 2D textures not look "bendy" on Ellipsoids.
Rename variable.
Merge branch 'grid-material' into ed-test-ellipsoid-dist
Set up a uniform and JS variable for maximum texture repeating on Ellipsoids.
Merge branch 'ed-test-ellipsoid-dist' into grid-material
Trying to make "lineThickness" values behave like pixel units.
Adjust default values.
Merge remote-tracking branch 'origin/master' into grid-material