THRIFT-388. Create a "ONEWAY" message type that is an alias for "CALL"

Pave the way for a new message type for oneway function calls.
For now, just define the constant in all languages and make
server implementations treat it the same way as a normal call.
Only C++ and Erlang currently check the message type (on the
server side).

There is a little bit of redundancy in the Erlang code, but
the alternative is a bit gross, and this split-up will be
necessary eventually when we start handling one-way calls
differently.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@761389 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/py/src/Thrift.py b/lib/py/src/Thrift.py
index 601b41c..21d7aa4 100644
--- a/lib/py/src/Thrift.py
+++ b/lib/py/src/Thrift.py
@@ -40,6 +40,7 @@
   CALL  = 1
   REPLY = 2
   EXCEPTION = 3
+  ONEWAY = 4
 
 class TProcessor: