Support for multiple connections per client

[crespum]

Currently when a client connects to the SATNET server (i.e. when it calls PasswordLogin AMP command), the server keeps track of the logged users by adding them to the dictionaries active_protocols and active_connections with the username as a key.

This implies that one user can only connect once and can only call StartRemote once. The consequence is that it can only use one channel.

I am considering two possible solutions based in changing the keys for those dictionaries (e.g. (username, channel)):

• Log in as many times as channels needed
• Log in once and call StartRemote as many times as needed

The problem is that on initialization channel will be equal to None and the dictionaries could contain repeated keys so I'm evaluating other designs.