Introduced a new shader composition example based on the new #pragama and #define based GLSL shader/osg::StateSet::setDefine() functionality now built into the core OSG.
git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14692 16af8721-9629-0410-8352-f15c8da7e697
creation of main shader to ShaderComposer and
collection of ShaderComponent to osg::State.
Also added very basic shader set up in osgshadecomposition example.
