Decomposing scavenge and added stone.

A basic function for decomposing scavenged material. I also had to add
stone to the components.xls file. I was not there and it was necessary.
Removed an unused line of code.

This commit added basic decomposing of items in
player.decomposeScavenged()
I also had to add stone to the components.xls
Merge pull request #30 from Tuxinet/master

Basic decomposing.