Fix #367 Mercator caching is broken; added a getCacheBin to setTargetProfileHint so that layers will know where to start looking in cache only mode
Fix #325 ModelNode et al do not serialize the properties from base class LocalizedNode
Add RenderSymbol::backfaceCulling property, Fix #328
Remove ModelLayer::overlay property
Fix: forgot to remove overlay directive
set PMA=off as MP default
Added option to specify an override profile to the mb tiles driver

Also added an optional profile to the mbtiles metadata that you can
specify to use global geodetic tiles
Merge branch 'master' of https://github.com/gwaldron/osgearth
Add simple HF validation to ElevationLayer to avoid loading corrupt files
Remove tex coord sharing and consolidate primitive sets in MP, even for mercator globes
MP: add per-GC uniform handling in MPGeometrY
Merge branch 'master' of github.com:gwaldron/osgearth
MP: Make MPGeometry multi-GC safe and replaced osg::Uniform usage with straight up GL
Removed the old MDI test code from the qt_simple example
VirtualProgram: repaired a faulty locking situation with accumulated function maps
Code cleanup in terrain engine
VirtualProgram: protect program upon first creation
Fix #375 Crash in VertexCacheOptimizer. It was actually a defiency in MeshSubdividier not properly dealing with vertex attribute arrays.
Removed some unnecessary utility methods in ShadowUtils.
Merge branch 'master' of https://github.com/gwaldron/osgearth