Created a new GraphicsThread subclass from OperationThread which allows the
GraphicsContext specific calls to be moved out of the base OperationThread class.
Updated the rest of the OSG to respect these changes.
Added and cleaned up DeleteHandler calls in osgViewer to help avoid crashes on exit.
Changed DatabasePager across to dynamically checcking osg::getCompileContext(..)
Updated wrappers.
so I' ve set up a macro that uses the variable name expanded for linking, and test if a variable ${LINK_VAR_NAME}_DEBUG
like OPENTHREADS_LIBRARY_DEBUG exists and in case uses it for linking in debug mode.
I' ve also set up FindOpenThreads to set up these variables.
I had to edit the core libraries CMakeLists to add the calls to the macros used.
I' ve tested under MSVC"
