Changed default screen size to match TRMNL OG

main.cpp

@@ -33,7 +33,7 @@ int main(int argc, char **argv)
 	bool ok;
 
 	int screen_width = 800;
-	int screen_height = 600;
+	int screen_height = 480;
 	string output_filename = "trmnl.png";
 	string cfg_filename = "config.json";
 	json cfg;