Canister wasn't flammable

Exploding items can now STORE their spark count at the time they were planted, allowing for bombs of different sizes to be detonated together. You can also set a max and min sparks if you want the size to be within a random range.

if the spark collision angle is < 45 then the sparks will split and bloom otherwise it'll fizzle. This better simulates fire flowing and spreading against an obstacle. Also upped default sparks to 800 and torus pressure to 0.4 because 404 chill not found. Merry xmas.

Added a constant for Directional Vector in Defs.lua to allow someone to set this to 0,0,0 for explosions that do not go "up". This is useful for a space explosion.
Tweaks to default values.