some J3D/misc cleanup (#2628)

* some j3d cleanup

* begin using uintptr_t

* j3dgraphbase cleanup

* j3dgraphanimator cleanup

src/d/actor/d_a_npc_grc.cpp

@@ -387,7 +387,7 @@ int daNpc_grC_c::CreateHeap() {
     for (u16 i = 0; i < mdlData_p->getJointNum(); i++) {
         mdlData_p->getJointNodePointer(i)->setCallBack(ctrlJointCallBack);
     }
-    model->setUserArea((u32)this);
+    model->setUserArea((uintptr_t)this);
 
     field_0xbd8 = 0;