servePut and clientPut implementation

Made the data-length header required even for v0. This simplifies the
implementation, and doesn't preclude extra verification being done for
v0.

The connectionWaitVar is an ugly hack. In servePut, nothing waits
on the waitvar, and I could not find a good way to make anything wait on
it.

Annex/Proxy.hs

@@ -59,8 +59,8 @@ proxySpecialRemoteSide clientmaxversion r = mkRemoteSide r $ do
 	let remoteconn = P2PConnection
 		{ connRepo = Nothing
 		, connCheckAuth = const False
-		, connIhdl = P2PHandleTMVar ihdl iwaitv
-		, connOhdl = P2PHandleTMVar ohdl owaitv
+		, connIhdl = P2PHandleTMVar ihdl (Just iwaitv)
+		, connOhdl = P2PHandleTMVar ohdl (Just owaitv)
 		, connIdent = ConnIdent (Just (Remote.name r))
 		}
 	let closeremoteconn = do