better explosions, GC improvements.

 Adds the trange function, a lot better than the range function since it only checks for turfs and not everything.

Altered explosion code to work using the Trange function, large explosions are now 'properly detected' and measures are taken to reduce the load it has on the server.
Grille and windows are now partially garbage collected, this is a better method as it allows BYOND to delete in it's own time. And thus is lighter on the game.
Effects are now deleted on a randomized timer to allow for a self-created "Garbage collector", it's lighter on the CPU, as well.
Destroying lights during a large explosion no longer spawns sparks, it doesn't look as good, but it helps a LOAD.