Speed modifiers (#19845)

Ported and implemented movespeed_modifer, for most things, from TG.
Gave deprecation DMDocs to the old calculation system.
Some code cleanup around.

code/modules/admin/callproc/callproc.dm

@@ -92,22 +92,24 @@
 				if(!object)
 					return
 
-				var/list/types = typesof(/atom)
+				var/list/types = typesof(/datum)
 				var/list/matches = new()
 
 				for(var/path in types)
 					if(findtext("[path]", object))
 						matches += path
 
-				if(matches.len==0)
+				if(!length(matches))
+					tgui_alert("No matches found for typepath [object].")
 					return
 
 				if(matches.len==1)
 					current = matches[1]
 				else
-					current = input("Select an atom type", "Spawn Atom", matches[1]) as null|anything in matches
+					current = input("Select a typepath", "Typepath Selection", matches[1]) as null|anything in matches
 
-				if(isnull(current)) return
+				if(isnull(current))
+					return
 
 			if("obj reference")
 				current = input("Select object for [arguments.len+1]\th argument") as null|obj in world