Several changes to Mackie support. Breaks existing Mackie state on disk but not

Several changes to Mackie support. Breaks existing Mackie state on disk but not
in any way that causes problems, just loss of pre-existing connectivity.

1. retain state of current device (and serialize to disk) when switching
devices, and restore that state when switching back to it.
2. fix port and surfacenaming.
3. fix bundle assembly so that all ports (for multi-surface combos) work.
4. rationalize master position numbering
5. add small sleep before starting device handshake after reconnection. This
is ugly but seems to be necessary, unfortunately.