Horse upgrade

Hi Developer,

you got an option to protect farm animals from being despawned:

ProtectedFarmAnimalSaveInterval: 6000
NumAnimalsForFarm: 3

Could you add a feature to the horses with would do the same. Because tamed horses will not despawn but they should if noone "uses" them for a certain amount of time. An maybe a playerlimit for taming horses if possible :)
