Added read callback to ElevationQuery to allow paged models to fully load.
Added check for modifying shared VirtualPrograms when environment var is set.
Added ability to log an individual VirtualPrograms' shaders to a file or std::out.
Merge branch 'master' of https://github.com/gwaldron/osgearth
added tile keys and widths to debug
Optimized the normal map shader
updates to tests
Merge branch 'master' of https://github.com/gwaldron/osgearth
NormalMap: fixed erroneous uniform constructors
SimpleModel: prevent page-out when the model's PagedLOD bound misses cull
NormalMap: fix bad merge
Merge branch 'master' of https://github.com/gwaldron/osgearth
wip..
VP: compilation error patch
Fix #2
Merge branch 'master' into topic-pagedlod-bbox
MP: add tile-LTP bbox culling for PagedLOD nodes, reducing memory usage an unnecessary paging activity.
Merge pull request #2 from gwaldron/master

Sync with master.