Finished implementing refresh in a separate thread.

src/renderer/structs.rs

@@ -1,3 +1,11 @@
+use sdl3::{Sdl, render::Canvas, ttf::Font, video::Window};
+
+
+pub struct Screen<'a> {
+    pub(crate) canvas: Box<Canvas<Window>>,
+    pub(crate) font: Box<Font<'a>>,
+    pub(crate) context: Box<Sdl>
+}
 
 pub struct Prefs {
     pub font_path: String,