Xconq checkins

[Stan Shebs <shebs at shebs dot cnchost dot com>]

Continuing to work through the consequences of the view object
change; the latest batch of checkins fixes AI and tcl/tk display
code that used to look directly at units, then try to figure out
how much they were allowed to see.  Now they can just assume the
view objects are correct and look at them only.

Also, the Gettysburg game now makes real use of visibility.
First, at night you can only see adjacent units.  (This could be
adjusted to a 2-hex range if anyone cares to argue that a night
marching column was visible 600 yards/meters away...)  Second,
units have a 50% chance to be seen in light woods, orchards, or
town, and 25% in heavy woods, unless they're adjacent, in which
case they're always visible.  (There is a remaining bug here
where if the woods were under observation from a distance and
you didn't see anything, moving adjacent doesn't always reveal;
a mistaken optimization in coverage calcs.)

Finally, I added some links to some nice high-performance mirrors
on the download page.

Stan