Expose a register function to register new custom binding routines.

@@ -76,6 +76,9 @@
   bidirectionals = ['value', 'checked', 'unchecked', 'selected', 'unselected'];
 
   rivets = {
+    register: function(routine, routineFunction) {
+      return bindings[routine] = routineFunction;
+    },
     bind: function(el, adapter, contexts) {
       var attribute, context, keypath, node, path, type, _i, _len, _ref, _results;
       if (contexts == null) {

@@ -65,8 +65,12 @@ bindings =
 # to propogate those changes back to the model object.
 bidirectionals = ['value', 'checked', 'unchecked', 'selected', 'unselected']
 
-# The rivets module. Exposes a single `bind` function.
+# The rivets module exposes `register` and `bind` functions to register new
+# binding routines and bind contexts to DOM elements.
 rivets =
+  register: (routine, routineFunction) ->
+    bindings[routine] = routineFunction
+
   bind: (el, adapter, contexts = {}) ->
     for node in el.getElementsByTagName '*'
       for attribute in node.attributes