Move app-wide defines into their own header

include/App.h

@@ -1,14 +1,12 @@
 #pragma once
 
 #include "AMI.h"
+#include "defines.h"
 
 #include <SDL2/SDL.h>
 
 #include <memory>
 
-constexpr int SCREEN_WIDTH = 480;
-constexpr int SCREEN_HEIGHT = 320;
-
 enum class AppView { AMI, DRIVER, TESTING };
 
 class SDLManager {

include/defines.h

@@ -0,0 +1,4 @@
+#pragma once
+
+constexpr int SCREEN_WIDTH = 480;
+constexpr int SCREEN_HEIGHT = 320;

src/AMI.cpp

@@ -1,6 +1,6 @@
 #include "AMI.h"
 
-#include "App.h"
+#include "defines.h"
 #include "util.h"
 
 AMI::AMI(SDL_Renderer* renderer)