This patch:

- Fixes a longstanding urb unlink race, by switching to a single queue
  for EDs being unlinked.  The previous two-queue scheme was sensitive to
  IRQ latencies:  one extra millisecond would make it use the wrong queue.
  This updated scheme should handle latencies of up to 32K microseconds
  (Cthulu forfend :) and slightly shrinks object code size.

- Related (mostly) cleanup.  Some functions and one ED field renamed, ED
  layout is a smidgeon more compact (even given more data), driver version
  string doesn't reflect CVS, debug message only comes out in verbose mode.