Pry::WrappedModule: add candidates Enumerator

This enables things like this: Pry::WrappedModule(mod).candidates.find(&:source)
returns the first candidate (monkeypatch) with accessible source code.

lib/pry/wrapped_module.rb

@@ -229,13 +229,21 @@ def candidate(rank)
       @memoized_candidates[rank] ||= Candidate.new(self, rank)
     end
 
-
     # @return [Fixnum] The number of candidate definitions for the
     #   current module.
     def number_of_candidates
       method_candidates.count
     end
 
+    # @return [Enumerator]
+    def candidates
+      Enumerator.new do |y|
+        (0...number_of_candidates).each do |num|
+          y << candidate(num)
+        end
+      end
+    end
+
     # @return [Boolean] Whether YARD docs are available for this module.
     def yard_docs?
       !!(defined?(YARD) && YARD::Registry.at(name))