Allow different level ranges for different actor types

[Zonk]

Currently zones allow a single level range which affects traps, NPCs, items....

My suggestion: allow to set separate ranges for traps/NPCs/items - although by default, a single level range would still be used for all three.

It shouldn't be too hard and I think it has potential for special zones which have say, extra deadly traps, or weak foes with particularly good treasure, and so on.

Could also be used for the higher difficulties, where you'd want more powerful foes and traps but not loot.

[darkgod]

done