[Paraview] plugin proxy timing issue

[Utkarsh Ayachit]

> 1) Receive aboutToRemoveServer, serverAdded, aboutToRemoveServer, serverAdded (twice when the self connection is closed and a pvserver connection is made. This is not a problem, but nonetheless odd and probably a bug.

That sounds very fishy. I'll take a look at this.
(http://paraview.org/Bug/view.php?id=12237)

> 2) plugins on the client, receive serverAdded, before plugins on the server have been loaded, so if they try to create proxies via the proxymanager - they fail because the server doesn't have them yet and can't create them.

That's interesting. I didn't realize this use-case. Let me try to
restructure the plugin-auto-loading mechanism to ensure that the
plugins are loaded before the serverAdded gets fired. The fix would be
auto-load server-side plugins in aboutToAddServer (or whatever the
corresponding signal is called).

Utkarsh