Multiple connections and connection bookmarks

[fenhl]

Users should have the ability to:

• Have multiple active connections at the same time (e.g. auto-track with RetroArch or Project64 and forward to a networked tracker room)
• Save a connection as a bookmark that can then be re-used with one click
• Set a bookmarked connection to auto-connect when the tracker is launched
• Use write-only connections from within the BizHawk plugin