Extract sc_display from sc_screen

Move the display code to a separate component.

app/src/display.h

@@ -0,0 +1,37 @@
+#ifndef SC_DISPLAY_H
+#define SC_DISPLAY_H
+
+#include "common.h"
+
+#include <stdbool.h>
+#include <libavformat/avformat.h>
+#include <SDL2/SDL.h>
+
+#include "coords.h"
+#include "opengl.h"
+
+struct sc_display {
+    SDL_Renderer *renderer;
+    SDL_Texture *texture;
+
+    struct sc_opengl gl;
+    bool mipmaps;
+};
+
+bool
+sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps);
+
+void
+sc_display_destroy(struct sc_display *display);
+
+bool
+sc_display_set_texture_size(struct sc_display *display, struct sc_size size);
+
+bool
+sc_display_update_texture(struct sc_display *display, const AVFrame *frame);
+
+bool
+sc_display_render(struct sc_display *display, const SDL_Rect *geometry,
+                  unsigned rotation);
+
+#endif