Added occlusion culling max altitude to IconSymbol; renamed elevation to altitude throughout OC code
Merge branch 'master' of github.com:gwaldron/osgearth
Fixed GPU clamping bug under MP, wherein the RTT depth camera was taking a picture of the right thing but at the wrong LOD.
FIX: empty VirtualProgram was not working properly; restore DepthOffset defaults.
Merge branch 'master' of github.com:gwaldron/osgearth