Loads-a-fixes for dev (#2515)

Fixes #2488 .
Fixes #2489 .
Fixes the bug of dying upon spawn.
Fixes new player recognition.

code/game/objects/effects/landmarks.dm

@@ -18,7 +18,7 @@
 			delete_me = 1
 			return
 		if("start")
-			newplayer_start += loc
+			newplayer_start = get_turf(loc)
 			delete_me = 1
 			return
 		if("JoinLate")

code/game/objects/items/weapons/tanks/jetpack.dm

@@ -24,6 +24,9 @@
 		if (R.module)
 			for (var/obj/item/weapon/tank/jetpack/J in R.module.modules)
 				return J
+		// Synthetic jetpacks don't install into modules. They go into contents.
+		for (var/obj/item/weapon/tank/jetpack/J in R.contents)
+			return J
 
 	return null