Sync default port with Use encrypted connection

Sync default port with Use encrypted connection

Change the preselected port from 6667 to 6697 when enabling
"Use encrypted connection" and change back from 6697 to 6667 when
disabling "Use encrypted connection".  The port number can be
manually changed, stopping the link between checkbox and port.
Existing networks are unmodified.

Add loosely-standardized default IRC server ports to network.h to
provide a central place to manage it.  This should only be used when
first adding a server.

See https://freenode.net/news/port-6697-irc-via-tlsssl