Add heightmap component and associated driver for ground following
Switch to full color heightmap and using one point to estimate instead of four
Separate simple heightmap calculation from a more-accurate commented-out version
Correct height dividend and improve variable name
Suspend the queue while heightmap is loaded and resume when finished

We were running into situations where a node was trying to query the heightmap before it had finished loading.  No more.
Merge pull request #341 from virtual-world-framework/mars-game-staging

merging