Converted ViewportQuad to use the material system
Some doc and cleanup
More doc and cleanup
Implement simple texture mapping as an alternative to using the material system
Update to ViewportQuad doc example.
Added emission component to final material color.
Initial ViewportQuad test
Removed picking code
fixed ViewportQuad tests
Code cleanup
Removed ViewportQuad custom texture shader.
Merge branch 'master' of https://github.com/gbeatty/cesium into ViewportQuad
New exception test for ViewportQuad
various code cleanup items
removed getRectangle() and setRectangle() methods on ViewportQuad and replaced with public property
doc fix for ViewportQuad.js
updated CHANGES.md
CHANGES.md update
Merge branch 'master' of https://github.com/gbeatty/cesium into ViewportQuad
Merge pull request #482 from gbeatty/ViewportQuad

Converted ViewportQuad to use material system
fixed broken `ViewportQuad` test
Merge pull request #496 from gbeatty/ViewportQuad

fixed broken `ViewportQuad` test
Updated CHANGES.md for b13