rare chance of special resources when harvesting

[Vlek]

Rare chance should be added for gems, gold nuggets, gems, and special items from mining.

Also special tree based resources, like bird's nests, from lumberjacking.

[Vlek]

I'm getting jewels when mining, it was just at higher levels that the jewels started.

Still need to double-check whether this is the case for lumberjacking, fishing, etc.