Compiling OSX doesn't automatically imply OSX tar.

Hopefully, detecting the underlying OS will help there.
Merge pull request #1967 from narc0tiq/osx-cross-detect

Compiling OSX doesn't automatically imply OSX tar.
Add FMJ versions of many ammunition types.
Add gold as a crafting material and add it to ammunition crafting recipes.
Add new fmj rounds to item spawn lists.
Implemented lua scripting for iuse.