Added basic code injection fields to osg::Shader,

creation of main shader to ShaderComposer and
collection of ShaderComponent to osg::State.
Also added very basic shader set up in osgshadecomposition example.

src/osg/Shader.cpp

@@ -201,7 +201,8 @@ Shader::Shader(const Shader& rhs, const osg::CopyOp& copyop):
     _type(rhs._type),
     _shaderFileName(rhs._shaderFileName),
     _shaderSource(rhs._shaderSource),
-    _shaderBinary(rhs._shaderBinary)
+    _shaderBinary(rhs._shaderBinary),
+    _codeInjectionMap(rhs._codeInjectionMap)
 {
 }