- split softc size and match/attach out from cfdriver into
a new struct cfattach.
- new "attach" directive for files.*. May specify the name of
the cfattach structure, so that devices may be easily attached
to parents with different autoconfiguration semantics.
changes by me:
* Make autoconfiguration work correctly for more models of AT1700.
* Make the debugging code more robust and complete.
* Tweak the output routine for better performance, and to eliminate an ugly
kluge.
Various other style cleanup. Needs more work.
