Merge pull request #222 from SkyMarshal/master

Reworked the mail system so it is almost flawless

code/modules/recycling/disposal.dm

@@ -932,6 +932,7 @@
 	desc = "An underfloor disposal pipe with a package sorting mechanism."
 	icon_state = "pipe-j1s"
 	var/list/sortType = list()
+	var/list/backType = list()
 	var/backsort = 0 //For sending disposal packets to upstream destinations.
 	var/mailsort = 0
 	var/posdir = 0
@@ -961,6 +962,12 @@
 
 	nextdir(var/fromdir, var/sortTag, var/ismail)
 		//var/flipdir = turn(fromdir, 180)
+		var/isback = 0
+		if(sortTag)
+			for(var/i, i <= backType.len, i++)
+				if(sortTag == src.backType[i])
+					isback = 1
+
 		if(fromdir != sortdir)	// probably came from the negdir
 
 			var/issort = 0
@@ -970,13 +977,14 @@
 
 			if(issort || ((!sortTag || ismail) && mailsort)) //if destination matches filtered type...
 				return sortdir		// exit through sortdirection
-			else if (backsort && sortTag)
+			else if (isback)
 				return negdir
 			else
 				return posdir
 		else				// came from sortdir
-							// so go with the flow to positive direction
-			return posdir
+			if(isback)
+				return negdir
+			return posdir	// so go with the flow to positive direction
 
 	transfer(var/obj/structure/disposalholder/H)
 		var/nextdir = nextdir(H.dir, H.destinationTag, H.tomail)