Explosives Update: Unify explosive item code and add new features

[Southclaws]

There are 9 explosive items in the game and they all have duplicate code. This needs to be addressed not only for design reasons but also so new explosive items can be added very easily.

Trigger types and some proposed updates:

• Timed (with various different times, settable by the user)
• Radio triggered (goodbye phones, cell towers wouldn't work in the apocalypse anyway)
• Proximity triggered (same as before)
• Trip mines (same as before, maybe add the ability to install into vehicles to explode when driven)

We already have IEDs, TNT and EMP but I'd like to implement a few others so there is a wider choice to craft for various different jobs. Explosive types:

• IED: maybe add more crafting requirements or make a new primer that isn't fireworks (craftable)
• TNT: no changes here
• EMP: this needs to disable stuff and not just stun, such as vehicles or other devices (radio/chat?)
• Incendiary: Petrol bombs need to happen, along with some kind of burning effect maybe...
• Thermite: maybe not so much an explosion but more of a defence burner
• Nail/Shrapnel: not great against defences but wreckage against people's bleedrate

Also: I've wanted to add this for a long time but explosives need to trigger other nearby explosives so a chain of explosions can happen. This needs to happen just for the pure awesome factor.

[Southclaws]

Work in branch explosive-update

[Southclaws]

Progress:

• Explosive item definition module completed
• Timed explosive items done
• Other explosion types added to presets
• All individual explosion modules removed

[Southclaws]

Finished existing explosives, will probably leave adding new ones until later. Will merge to master after some testing.

Need to test screwdriver defusing and any other explosive interactions (search for mentions of explosive itemtypes)