Add _.functionsIn and _.pairsIn.

test/underscore.html

@@ -277,6 +277,9 @@
             'assigning non-objects results in returning the non-object value',
             'assigning undefined results in undefined'
           ],
+          'functions': [
+            'also looks up functions on the prototype'
+          ],
           'isEqual': [
             '`0` is not equal to `-0`',
             'Commutative equality is implemented for `0` and `-0`',