Ports /tg/'s meteor implementation.

Merges the two meteor events into one, and now takes severity into consideration instead.
Including the basic meteors there are also new types ranging from flaming to radioactive which may drop appropriate types of ore.

code/modules/admin/verbs/icarus.dm

@@ -111,11 +111,10 @@ proc/Icarus_FireCannon(var/turf/target)
 	target = locate(x, y, target.z)
 
 	// Finally fire the fucker.
-	var/obj/effect/meteor/small/projectile = new (start)
+	var/obj/effect/meteor/projectile = new (start)
 	projectile.dest = target
 	projectile.name = "main gun projectile" // stealthy
 	projectile.hits = 6
-	projectile.detonation_chance = 99 // it's a missile/cannon round thing!
 
 	// Make sure it travels
 	spawn(0)