KML tweaks; depth offset support in FMG
Merge branch 'master' of github.com:gwaldron/osgearth
tweak to the overlaydecorator to ensure that depth field sampling penetrates the terrain
Fix top-level bounding sphere issue in FMG
Fixed TileCache driver to not be off by one lod.
Merge branch 'master' of https://github.com/gwaldron/osgearth
Merge branch 'upstream/master'