Server prep: reword messages to be client/server agnostic.

Lots of user-facing messages that claim that the 'server' just did
something or other unexpected will now need to be issued _by_ the
server, when the client does the same unexpected thing. So I've
reworded them all to talk about the 'remote side' instead of the
'server', and the SSH-2 key setup messages talk about initialising
inbound and outbound crypto primitives rather than client->server and
server->client.

sshverstring.c

@@ -392,7 +392,7 @@ void ssh_verstring_handle_input(BinaryPacketProtocol *bpp)
 
   eof:
     ssh_remote_error(s->bpp.ssh,
-                     "Server unexpectedly closed network connection");
+                     "Remote side unexpectedly closed network connection");
     return;  /* avoid touching s now it's been freed */
 
     crFinishV;