Add PolylineGlowMaterialProperty

This allows for DynamicScnee materials to make use of the PolylineGlow type.

Note, CZML does not support this material yet.
Merge remote-tracking branch 'origin/master' into polylineGlow

Conflicts:
	CHANGES.md
Merge remote-tracking branch 'origin/master' into polylineGlow

Conflicts:
	CHANGES.md
Cleanup after merge.
Merge remote-tracking branch 'origin/master' into polylineGlow

Conflicts:
	CHANGES.md
Merge pull request #1500 from AnalyticalGraphicsInc/polylineGlow

Add PolylineGlowMaterialProperty