More Xconq bug fixes

[Hans Ronne <hronne@telia.com>]

I have checked in a number of improvemets to the repair and resupply code.
I believe that most of the bugs in this code, some of which were serious,
have now been fixed. This means that units no longer get trapped in reserve
mode because of failed repair tasks etc.

Other recent improvements:

1. The ai now knows how to do explicit repair, at least for the same unit
(self-repair).

2. The ai has been improved, in particular its action reaction code and
responsiveness when switched on and off.

3. Colonizing units now behave a little more intelligently.

4. Several kernel bugs affecting combat model 1 games such as civ2 have
been fixed.

5. A new unit namer "in-order" picks names in order instead of randomly
from a name list. This is a useful game design feature that has so far been
missing.

6. A serious bug in the unit-wrecking code has been fixed.

7. Several bugs affecting self-units have been fixed, and the associated
messages have been improved.

8. Several bugs in the MacPPC interface have been fixed.

9. Most of the remaining graphics problems on Windows have been fixed.
Terrain transitions, overlays and unseen fuzz are now drawn also on
Windows, and the "black-is-transparent" and "translucent edge cell" bugs
have been fixed.

10. BWidget has been updated to 1.6.0.

11. The tcltk help window has been overhauled. The advances tree is now
drawn correctly also in the MacTCL interface.

12. The help node headings suggested by Richard Hunt have been implemented.

This burst of activity does not mean that I have given up on updating the
lib and doc files before making a pre-release. However, going through all
the games and testing them did reveal a number of more or less severe
kernel bugs that I was unaware of. Hence the above fixes.

Hans