[freeciv-ai] ai hp recovery patch v7

["Per I. Mathisen" <per@xxxxxxxxxxx>]

I've made some changes to the patch (minor) and adapted it to fit on top
of my bodyguard cleanups and use the ai_military_rampage() function.

There is one change I think should be done, however: Currently it sends
units back to rest at 25% hitpoints. But after some pitfights, I think it
should do this at 50%.

I ran a few pitfight games, and here are the (quite surprising) results:

                   'hard' : 'experimental' (ie w/ patch)
50%                     8 :  18
50% + triggerhappy      7 : 8
25%                    18 : 12
no changes              6 : 10  (control group)

I suppose that this is happening because units at 25% are so weak that
they take forever to return, while units at 50% can return reasonably
quickly and then come back to action. Still I am not convinced I really
understand why the difference is that big....

Whether the good results at 50% are because of the healing or because it
keeps more units in defense (while healing) is also an open question.

Finally, when it enters recovery mode, it will only scoop up empty cities
on its way to safety. It might be better to attack more liberally even
though we are weakened. This is "triggerhappy" refered to above. For some
strange reason this evens out the difference between 25% and 50%, however.
But to measure this difference I think I will have to run pitfight games
between two players that both have recovery turned on with same % but with
triggerhappiness as only difference, as it is difficult to measure the
difference statistically otherwise.

Oh, and anyone know settings/patches that can be used to speed up pitfight
games?

Yours
Per

recover_hp7.diff
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