Cleaned the interrupt code a bit

src/interrupts.h

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2022 Dominic Masters
+ * 
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "libs.h"
+#include "conversation/textbox.h"
+
+#define INTERRUPT_TEXTBOX_VRAM ((TEXTBOX_WIN_Y * TILE_HEIGHT) - 1)
+
+void interruptOnScanline();