Updated join game dialog

* Support custom network ports (both server and client)
* Add "edit server" 
* Add some usability features (tabbing, copy name to address) in the "Add Server" popup - fixes #1074
* Reorganized buttons  in "Join Game" screen
* Replaced "Join Direct" popup with console commands `join` and `leave` (Closes #1098)
* Wrapped remaining internal Protocol Buffer class in `ServerMessageInfo` - preparing for #1099