Realistic Horse Genetics

Herd behaviour and natural breeding update, thanks to dexpere for supporting development!

Also adds a French translation, made by valentin56610, thank you!

Herd behaviour: Horses stay together in herds rather than wandering about aimlessly. Mares can form a herd with each other and with a stallion, who will chase away any competing stallions. Usually a lead mare will decide where the herd goes, though occasionally they will follow the stallion instead. If there are no mares around, stallions can get together as a bachelor herd. Geldings can join either herd type.

Small tweak: Mares will wait up a bit for their foals if they get too far away.

Natural breeding: If you enable "autobreeding" in the config, horses can reproduce without any player input. This should happen relatively slowly, and only while there are fewer than 16 horses within a 16 meter radius. I've slowed down the default settings for growth and pregnancy as well. Existing players, you'll only get that change if you regenerate the config. Wild horses can breed automatically. Tame horses can't by default, but if you enable it for them by clicking on the heart in the GUI, then they can too. Horses will almost always avoid automatically breeding with their immediate relatives (parents, children, siblings, half-siblings).

Bugfix: Fixed item duplication glitch.