Add a check in bzflag/index.vwf.yaml for players being null

refs #1762
Add guards in node3.vwf.yaml for null transform and boundingBox

It had defaulted to undefined which wreaked havoc on the worldTransform getter.  This commit also places a check in that getter to guard against null/undefined values that get set later.
refs #1762
Add default background color to scene.vwf.yaml
Add sourceUrl to hmvee.vwf.yaml to aid in debugging
Remove glgeLight from radio app so it works more consistently