allow ammo metals

- brass, lead and platinum can be used as ammo

There are some kinds of ammo that you can create, but cannot assign to
squads because the materials are missing the [ITEMS_AMMO] tag. I've
updated the ones I found to be missing, but there may be more.
exported options #102 and diggingInvaders #106

- allows the exporting of all the details of most options to a file.
it's messy. xml better maybe?
- changed the diggingInvaders button to simply disable the plugin in
dfhack.init, rather than adding #removed for every line
Merge branch 'gold' into orc_rebalance

* gold:
  exported options #102 and diggingInvaders #106
  allow ammo metals