use common gathering framework for milking.lua

* allow for rare items to occur occationally
* allow learn farming skill
Merge branch 'develop' of ssh://illarion.org:1010/scripts into develop
Fixing bug in base.factions
Merge remote-tracking branch 'Illarion/develop' into develop
Fixing GM tool to control the faction relations
Added missing texts to faction gm tool
Fixing some copy&paste mistakes in faction script