Merge lp://staging/~widelands-dev/widelands/ai_fisher_fix into lp://staging/widelands

Continuous integration builds have changed state:

Travis build 3323. State: failed. Details: https://travis-ci.org/widelands/widelands/builds/360061692.
Appveyor build 3130. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_widelands_dev_widelands_ai_fisher_fix-3130.

Famous last words *lol* - I have done some minimal testing.

@bunnybot merge

Refusing to merge, since Travis is not green. Use @bunnybot merge force for merging anyways.

Travis build 3323. State: failed. Details: https://travis-ci.org/widelands/widelands/builds/360061692.

fix is not working. Reason is that the algorithm counts all fish in the working radius, but fishermen only are able to extract the fish from the coast so even if there is no catchable fish at all. AI will (and is doing so in my tests) continue to build fishermen huts. Only thing is they now will be build in a region of 6 around the coast instead of 7 around the coast, cause the first water field had been emptied. So as the current game adds default fish to the maps where no fish is defined, we can't solve it in the editors. best thing would be to check whether there is a walkable and reachable field near the ressource befor considering it to be nearby

Indeed, this fix does not cover situation when fish are there but not reachable from coast.

But eliminates possibility of building a fishers hut in vicinity of water without fish at all.

I will modify the code once more...

OK, so I did it hard way, please test now

(some cleanup needed before merging)

still not working properly
see replay

didn't know how to add somethign to the branh so I created a bug reprot and added my replay there it shows both the fisher problem not being fixed and the problem with the non conquered mountain area

Did a playtest of the algorithm.
Code cleanup looks good.
Thanks to Tibor for his patience and support

Continuous integration builds have changed state:

Travis build 3351. State: passed. Details: https://travis-ci.org/widelands/widelands/builds/363043830.
Appveyor build 3157. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_widelands_dev_widelands_ai_fisher_fix-3157.

LGTM - just 1 nit for a comment. Please merge once it's fixed :)

OK, fixed, merging now
@bunnybot merge