Add TerrainInspector app.
Enable terrain and fix a race condition.

The race could makes tiles sometimes not show up as wireframe when they
should.
Show bounding spheres and render only selected.
Merge remote-tracking branch 'origin/master' into terrainInspector

Conflicts:
	Source/Scene/Tile.js
Remove commented-out code.
Changes suggested by Scott.
Move javascript to a separate file.
Use defined function.
Merge remote-tracking branch 'origin/master' into terrainInspector
Fix warnings.
Add Terrain Inspector to index.html.
Merge pull request #1017 from AnalyticalGraphicsInc/terrainInspector

Add TerrainInspector app.