Camera Preparation (#644)

* Copy progress from z_camera

* cleanup functions.h

* Oops

* Revert `SUB16` and `ADD16` back to original names

* PR Suggestions

* PR Suggestions

* Fix merge with master

src/code/z_shrink_window.c

@@ -2,6 +2,7 @@
  * File: z_shrink_window.c
  * Description: Draws black top/bottom/side borders on the viewing window (e.g. Z-targeting, talking to NPC)
  */
+#include "prevent_bss_reordering.h"
 #include "global.h"
 
 ShrinkWindowContext gShrinkWindowContext;