Made the more of the OSG's referenced object desctructors protected to ensure

that they arn't created on the stack inappropriately.

Split the implemention of Matrix up so that it is a simple no referenced counted
class and can be safefly created on the stack.  To support referenced counting a
seperate subclass now exists, this is RefMatrix which inherits from both Matrix and
Object.

src/osg/Projection.cpp

@@ -4,18 +4,17 @@ using namespace osg;
 
 Projection::Projection()
 {
-    _matrix = new Matrix;
 }
 
 Projection::Projection(const Projection& projection,const CopyOp& copyop):
     Group(projection,copyop),
-    _matrix(new Matrix(*projection._matrix))
+    _matrix(projection._matrix)
 {    
 }
 
 Projection::Projection(const Matrix& mat )
 {
-    _matrix = new Matrix(mat);
+    _matrix = mat;
 }