OSG 2.6.1

OpenSceneGraph is a high performance 3D graphics toolkit, used by application developers in fields such as visual simulation, games, virtual reality, scientific visualization and modelling.
OpenSceneGraph is written entirely in Standard C++ and OpenGL and it runs on Mac OS X, Windows platforms, GNU/Linux, IRIX, Solaris, HP-Ux, AIX and FreeBSD operating systems.
The OpenSceneGraph is now well established as the world leading scene graph technology, used widely in the vis-sim, space, scientific, oil-gas, games and virtual reality industries.
NOTE: OSG is licensed and distributed under the terms of the Lesser Gnu Public License (LGPL).

Enhancements:
- Fix to OverlayNode from Jason Beverage.
- BlendEquation support in .osg/.ive
- Fix to FLT exporter to properly export PositionAttitudeTransform nodes.
- Change OcclusionQueryNode to workaround an OpenGL implementation issue on NVIDIA devices with Linux drivers. The workaround is to wait (in a loop) until the query result is ready before we retrieve it. This workaround can be enabled in cmake but is disabled by default.
- cmake targets for wrappers and changelog
- Change AutoTransform interface to use doubles; osgTerrain wrapper modification for Layer.cpp.
- cmake maintainer enhancements for tags.
- Fix to osgUtil::Simplifier to handle shared vertex arrays correctly. Changes the Geometry interface, so forces a recompile.
- Fix for uninitialized "strip texture path" option in OpenFlight exporter.
- Fix for FLT plugin user data handling.
- Modification to r8795 to sleep inside the loop that checks for availability of the occlusion query result.
- Bump OSG version number from 2.6.0 to 2.6.1.
- Update wrappers.