Support for buffer protocol for socket and struct.

* Added socket.recv_buf() and socket.recvfrom_buf() methods, that use the buffer
  protocol (send and sendto already did).

* Added struct.pack_to(), that is the corresponding buffer compatible method to
  unpack_from().

* Fixed minor typos in arraymodule.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 52a7f5e..af12769 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -1975,9 +1975,9 @@
 	0,					/* tp_setattr */
 	0,					/* tp_compare */
 	(reprfunc)array_repr,			/* tp_repr */
-	0,					/* tp_as _number*/
-	&array_as_sequence,			/* tp_as _sequence*/
-	&array_as_mapping,			/* tp_as _mapping*/
+	0,					/* tp_as_number*/
+	&array_as_sequence,			/* tp_as_sequence*/
+	&array_as_mapping,			/* tp_as_mapping*/
 	0, 					/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */