Adds fireplaces, eswords are hot, cardboard is flammable (#19118)

Makes needed improvements to proposed fireplaces

- Fireplaces now use world.timer
- Fireplaces no longer prompt input() for inserting logs, it just
takes as many logs as possible
- Paper and paper bins can be thrown on the fire, thirty paper is worth
one log of burn time.
- One log gives 15 seconds of burn time, the fireplace can hold up to 5
minutes of fuel.
- Ignitable items now use a /obj level proc to generate their messages,
currently using this are cigarettes, candles, fireplaces
- The fireplace can be put out with an extinguisher
- Cardboard cutouts are now flammable
- The fireplace is only "warm and cozy" when lit
- Paperbins qdel their stored papers when destroyed (probably did that
already, but no harm in making sure)
- Also removed some returns hanging around

* Added new proc for lighting stuff

- Adds ignition_effect(atom/A, mob/user) to obj/item, which is called
when you're attempting to light things with that object. By default it
does nothing and prevents ignition, but if the object is hot, it returns
a message. May do other things for different stuff.

- Eswords now ignite flammable gasses in their area.

* Fireplace is no longer on fire when not on fire

code/modules/reagents/chemistry/reagents/other_reagents.dm

@@ -125,7 +125,6 @@
 			G.temperature = max(min(G.temperature-(CT*1000),G.temperature/CT),0)
 			G.react()
 			qdel(hotspot)
-	return
 
 /*
  *	Water reaction to an object