Merge pull request #44825 from AutomaticFrenzy/patch/lints

In advance of eventually adding SpacemanDMM's linter to Travis, fix everything it can currently detect.

Some lists, including global lists, are given types so that L[i].foo expressions can be checked.

Some procs are given a new form of return type annotation so that DuplicateObject(O).forceMove()-type invocations can be checked.

Open to syntax suggestions on the return type annotations, and on whether the preprocessor strategy makes sense.

Return type syntax is currently roughly:

    <typepath> | <paramname>([_])*(.type)?

code/modules/vehicles/_vehicle.dm

@@ -61,6 +61,7 @@
 			.++
 
 /obj/vehicle/proc/return_controllers_with_flag(flag)
+	RETURN_TYPE(/list/mob)
 	. = list()
 	for(var/i in occupants)
 		if(occupants[i] & flag)