Fix: Ammo crate explosiveness

Ammo crate explosion power is now determined by how much explosive
content is inside the crate, rather than purely on ammo count.
Generally, expect less boom from smaller rounds, and more boom from big
rounds.
Merge pull request #21 from Fervidusletum/AmmoExplosion

Fix: Ammo crate explosiveness
Updated version number for Fervidusletum's ammo explosion fix (explosions based on explosive content).
Merge remote-tracking branch 'remotes/upstream/master'