improve support for UDI.

include/rtree_udi.h

@@ -0,0 +1,24 @@
+#ifndef _RTREE_UDI_
+#define _RTREE_UDI_
+
+#ifndef _RTREE_
+typedef void control_t;
+#endif
+
+/*Prolog term from :- udi(a(-,+,+)).
+  User defined index announce
+*/
+extern control_t *RtreeUdiInit (Term spec,
+                                void *pred,
+                                int arity);
+
+/*this is called in each asserted term that was declared to udi_init*/
+extern control_t *RtreeUdiInsert (Term t, /*asserted term*/
+                                  control_t *control,
+                                  void *clausule); /*to store in tree and return
+                                                     in search*/
+
+extern void *RtreeUdiSearch (control_t *control);
+extern int RtreeUdiDestroy(control_t *control);
+
+#endif /* _RTREE_UDI_ */