[9fans] VESA modes for VGADB

[9fans] VESA modes for VGADB

[lucio]

Following a suggestion on 9fans (thank you, whoever it was) I added
two sets of clock settings to VGADB courtesy of the VESA code in
aux/vga.

Recent updates to lib/vgadb prompted me to wonder how I could retain
the additional information and still replicate lib/vgadb from
"sources".  I'm looking for a more sensible answer than I came up
with.

It seems to me that we need a local VGADB option, not unlike
lib/ndb/local, but also that we need to enhance aux/vga to query the
VESA settings when looking for and not finding a monitor definition.
Precisely what protocol ought to be followed is the part I'm not
comfortable with.  If we can come up with a consistent approach, I
will try to implement it.

At this point, aux/vga as well as /dev/vga need a rethink, in my
opinion.  I seem to remember that this was also someone else's opinion
a long while ago.  I'm also looking for sensible suggestions on
enhancing the kernel and user-level handling of VGA (a) to be more
consistent with the Plan 9 approach and (b) to allow multi-head
operation.  Again, given enough guidelines, I am willing to attack the
implementation.

++L