Now with Atomicity

tests/task4.rs

@@ -1,8 +1,7 @@
 extern crate rustijvm;
 
 use std::io::{Cursor, Read, Seek, SeekFrom};
-use std::rc::Rc;
-use std::sync::Mutex;
+use std::sync::{Arc, Mutex};
 
 fn steps(machine: &mut rustijvm::Machine, num: usize) {
     for _ in 0..num {
@@ -84,7 +83,7 @@ fn task4_complex_load() {
 
 #[test]
 fn task4_iteration_load() {
-    let rc = Rc::new(Mutex::new(Cursor::new(Vec::new())));
+    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
 
     let mut machine = rustijvm::Machine::new_from_file("files/task4/LoadTest4.ijvm").unwrap();
     machine.set_output(rc.clone());