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
Start refactoring reference properties.
Merge branch 'master' into referenceProperties
Ongoing reference property work.
Merge branch 'master' into referenceProperties
Merge branch 'master' into referenceProperties
Merge remote-tracking branch 'origin/master' into referenceProperties
Ongoing ReferenceProperty work.
Ongoing ReferenceProperty work

Old tests all pass, update simple.czml so that it works again.
Add ability to reference sub-properties.
Ongoing ReferenceProperty work

Completely rewrite tests and refactor implementation to handle sub-properties and definitionChanged events.
Merge remote-tracking branch 'origin/master' into referenceProperties
Start adding CZML reference property tests
Specs and implementation for CZML reference property parsing.
Improve ReferenceProperty documentation.
More ReferenceProperty cleanup.

Also make local CZML references work (though implementation is a little hacky right now)
Move changes to 1.0.
Update outdated doc.
Merge remote-tracking branch 'origin/master' into referenceProperties
Fix crash do to use of undefined variable.