Added enabling of threadsafe ref/unref in FileCache.
Added enabling of threadsafe ref/unref in FileCache.


tomasthoresen/osg,artoolkit/osg,scrawl/osg,jtorresfabra/osg,artoolkit/osg,openscenegraph/osg,openscenegraph/osg,marchelbling/osg,jtorresfabra/osg,marchelbling/osg,openscenegraph/osg,tomasthoresen/osg,artoolkit/osg,artoolkit/osg,openscenegraph/osg,scrawl/osg,marchelbling/osg,tomasthoresen/osg,scrawl/osg,scrawl/osg,jtorresfabra/osg,jtorresfabra/osg,tomasthoresen/osg,marchelbling/osg