message: Set is_direct flag when doing a PM I->M
diff: @@ -127,7 +127,8 @@ IrcHandler.prototype._createPmRoom = Promise.coroutine(
  invite: [toUserId],
  creation_content: {
  "m.federate": server.shouldFederatePMs()
  - }
  + },
  + is_direct: true,
  }
  });
  let pmRoom = new MatrixRoom(response.room_id);
  