basectx: move manifest from changectx

basectx: move manifest from changectx

--- a/mercurial/context.py	Mon Aug 05 17:22:18 2013 -0500
+++ b/mercurial/context.py	Mon Aug 05 17:22:49 2013 -0500
@@ -73,6 +73,8 @@
         return self._node
     def hex(self):
         return hex(self.node())
+    def manifest(self):
+        return self._manifest
 
 class changectx(basectx):
     """A changecontext object makes access to data related to a particular
@@ -209,8 +211,6 @@
 
     def changeset(self):
         return self._changeset
-    def manifest(self):
-        return self._manifest
     def manifestnode(self):
         return self._changeset[0]