Add sdl2 handlers and bunch of tests

First semi-working state, games can be loaded and they open
a sdl2 window \o/

TODOS:
+ Stacks offset is wrong somewhere
+ Input not working (maybe because of above reason?)
+ Add mising tests

src/main.rs

@@ -5,12 +5,22 @@ use std::env;
 
 mod processor;
 mod fontset;
+mod display;
+mod input;
+mod cartridge;
 
 use crate::processor::Processor;
+use crate::cartridge::Cartridge;
+
+const MEMORY_SIZE: usize = 4096;
+const GAME_ENTRY: usize = 0x200; // most games load into 0x200
+const SCREEN_WIDTH: usize = 64;
+const SCREEN_HEIGHT: usize = 32;
+const SCREEN_SCALE: usize = 20;
 
 fn main() {
-    let cartridge = env::args().nth(1);
-    match cartridge {
+    let game_file = env::args().nth(1);
+    match game_file {
         Some(_) => println!("Found a cartridge file! Trying to load..."),
         None => {
             println!("No cartridge file found! Exiting!");
@@ -21,7 +31,8 @@ fn main() {
     let mut processor = Processor::new();
 
     // load cartridge file
+    let cartridge = Cartridge::new(&game_file.unwrap());
 
-    processor.start();
+    processor.start(&cartridge.rom);
 
 }