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.
on the stack thus ensure that they arn't created locally and have their
memory deleted incorrectly.
Also updated the IntersectVisitor so that it no used osg::ref_ptr<> internally
for storing all data. Have also move the IntersectState helper class to inside the
IntersectVisitor which simplifies the external interface to the class.
