[FEATURE] Unequip all on firegib

[Tombi]

Summary
Firegibbed mobs drop all equipped items (including held ones) onto the tile beneath them. Dropped equipment gains a singed prefix.

The discussion

The pull request

Tech Notes
/mob/proc/firegib() adds the singe_equipment and unequip_all methods which drops everything the mob is wearing/holding onto the tile the mob was on plus gives those items the 'singed' prefix.

PS. how's the format look? Thought I'd try something different, hope it is clear enough.

EDIT: singe prefix included

[Triacontakai]

yea there's no reason not to do this, especially since firegib sometimes doesn't even leave an ash pile

[Tombi]

Patch updated to include 'singed' prefix to dropped items. Something I noticed while testing is that some items (id and cash) get a bit wonky with their names - for instance the 1000 credits I had in my pockets became singed 1 credits while still retaining the 1000 credit icon sprite.