Reworked how napalm works to make it more powerful with the new turf
fires. Instead of directly creating a turf fire, it'll instead process a
slower burning, but deadly turf fire.
Also added a military-grade flamethrower, which can use the new napalm.
This will create napalm pools on the ground and ignite them, instead of
directly creating turf fires.
### Asset Licenses
The following assets that **have not** been created by myself are
included in this PR:
| Path | Original Author | License |
| --- | --- | --- |
| icons/obj/item/military_flamethrower.dmi | electricpants#6824
([Shiptest](https://github.com/shiptest-ss13/Shiptest)) | CC-BY-SA 3.0 |
