Refactor stack recipes

- Styling fixes
 - Added post_build() to stack recipes, for any recipes that need to do
   something special
   - Called with two arguments, the stack that it originated from, and the
     new object.
 - Moved stack recipes to their own file

Currently, only two things use post_build
 - Cablecuffs use it to color the cuffs the same as the wire they
   originated from
 - Metal rods use it to call update_icon, in order to display the correct
   sprite for whatever amount of rods you created.

code/modules/nano/interaction/base.dm

@@ -12,9 +12,9 @@
 	return STATUS_CLOSE
 
 /mob/proc/shared_nano_interaction()
-	if(src.stat || !client)
+	if(stat || !client)
 		return STATUS_CLOSE						// no updates, close the interface
-	else if(restrained() || lying || stat || stunned || weakened)
+	else if(restrained() || lying || stunned || weakened)
 		return STATUS_UPDATE					// update only (orange visibility)
 	return STATUS_INTERACTIVE