[core] [types] breaking change update to quadtree & octree

- update tree impls to use points as unqiue keys w/ attached data values
- update PSpatialTree protocol, split out PTreeOps (in spatialtree ns) for non-public ops
- update tree selection fns to return stored values, not the points they're indexed at
- update org structure of spatialtree ns

geom-core/src/core.org

@@ -541,17 +541,10 @@ protocol consisting of just this one function:
 
 #+BEGIN_SRC clojure :noweb-ref protos-types
   (defprotocol PSpatialTree
-    (add-point [_ p])
-    (child-index-for-point [_ p])
-    (child-for-point [_ p])
+    (add-point [_ p d])
     (delete-point [_ p])
-    (get-children [_])
     (get-point [_])
-    (set-child [_ i c])
-    (set-children [_ c])
-    (set-point [_ p])
-    (make-child-for-point [_ p add-point?])
-    (split-node [_]))
+    (get-point-data [_]))
 #+END_SRC
 
 *** Buffered instances