Refractor headers and split code into program files for app & localization files.

Split keybinds from window.h file. General cleanup

include/app/scene.h

@@ -0,0 +1,33 @@
+#ifndef SCENE_H
+#define SCENE_H
+
+#include "app/elements.h"
+#include "bindings/ruby.h"
+#include "utils.h"
+#include "window/window.h"
+
+namespace app {
+struct Scene {
+  std::vector<uint64_t> element_ids;
+  Ruby::Block update;
+
+  ~Scene();
+
+  void add_element(uint64_t element_id);
+
+  void delete_element(uint64_t element_id);
+  void update_scene(mrb_value dt_val);
+
+  void click(Vec2<float> position);
+
+  void render(uint64_t abs_time);
+
+  std::vector<uint64_t> elements_at(Vec2<float> position);
+
+  Vec2<float> world_to_local(Vec2<float> p, Element *e);
+};
+
+inline Pool<Scene> scene_pool;
+} // namespace app
+
+#endif