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/Matrix.cpp

@@ -24,12 +24,12 @@ using namespace osg;
 
 
 
-Matrix::Matrix() : Object()
+Matrix::Matrix()
 {
     makeIdentity();
 }
 
-Matrix::Matrix( const Matrix& other) : Object()
+Matrix::Matrix( const Matrix& other)
 {
     set( (const float *) other._mat );
 }