This should fix the health vial - apparently none of them work, not just the ones that drop from Combine.
Updates ammodef to have an itemid value. Since actual ammo types are discrete (no ammo shares the same value), this isn't an issue, and defaults to 0 to preserve HL2 behavior where relevant.
Revisions to recharging mechanics - chargers should now regenerate as in MP, and the Citadel mechanics have been revised.
Health warnings on the HUD now track upgrade status by respecting GetMaxHealth().