Build type information on first use (load-time), instead of using a hardcoded list

--HG--
branch : dynamiccore2

src/modules/physics/box2d/Contact.cpp

@@ -31,6 +31,8 @@ namespace physics
 namespace box2d
 {
 
+love::Type Contact::type(&Object::type);
+
 Contact::Contact(b2Contact *contact)
 	: contact(contact)
 {