Implemented firecrackers. #56
Increased sound volume. Set pack to 1 vol/weight, single firecracker to 0 vol/weight.
Merge pull request #239 from delebota/iss56

Firecrackers.
Base production of bone and sinew on a MF_BONE flag instead of MEAT, so insects, spiders, etc don't produce bones.
Make child zombies be made of zombie meat too.