Modify default dependency satisfaction timeout to 20s

Also, correctly print out number of seconds, not ms!
Store a simple history log of dependency updates for debugging purposes.
Fix regression introduced in #c3041 and auto-allocate audio-busses ids
that are already associated with hardware io. Don't use naive strategy
of allocating AUDIO-BUS-RESERVE-COUNT busses (previously 50!!) but 
instead aut-allocate the correct number of busses for the given hw.
Fix dependency graph to handle new ha-audio-bus-reserved dependency.
It's probably not ever sensible to reset busses when server is rebooted.
Given that they're coordinated ids, they are still good to go...
fix ugen docstring