Reorganize and refactor, adding integration test for common library stuff

tests/common_io_test.rs

@@ -0,0 +1,24 @@
+use common::io::{read_string, write_string};
+use std::io::Cursor;
+
+#[test]
+fn it_reads_strings() {
+    let buffer = [0x0, 0x3, b'F', b'o', b'o'];
+
+    assert_eq!(
+        read_string(&mut buffer.as_ref()).unwrap(),
+        "Foo".to_string()
+    );
+}
+
+#[test]
+fn it_writes_strings() {
+    let mut buffer = Cursor::new(Vec::new());
+
+    write_string(&mut buffer, "Foo").unwrap();
+
+    // Should have written exactly 5 bytes
+    assert_eq!(buffer.get_ref().len(), 5usize);
+
+    assert_eq!(&buffer.get_ref()[0..5], [0x0, 0x3, b'F', b'o', b'o']);
+}