Changes obj/effect/blob,spider,swarmer,energy_net,spacevines to be ob/structures instead, since you can hit and destroy them.

Adds a large ash and large molten item decal (for future use)
simplifies decal/cleanable/replace_decal() code a bit.
Changes construction() proc to on_construction() for consistency, same for deconstruction().
Made a deconstruct() proc for machinery and computer (also for future use).

code/modules/power/singularity/singularity.dm

@@ -64,7 +64,7 @@
 /obj/singularity/Process_Spacemove() //The singularity stops drifting for no man!
 	return 0
 
-/obj/singularity/blob_act(obj/effect/blob/B)
+/obj/singularity/blob_act(obj/structure/blob/B)
 	return
 
 /obj/singularity/ex_act(severity, target)