Add serialization to String

rs/src/main.rs

@@ -1,17 +1,7 @@
 mod board;
+mod ui;
 
 fn main() {
-    println!(
-        "{}",
-        match board::Board::new()
-            .get_at(&board::Position::new(board::Rank::_2, board::File::A))
-        {
-            Some(piece) => "Some",
-            None => "None",
-        }
-    );
-    // reset -> (ok/fail)
-    // get_state -> (ok/fail),state
-    // get_moves,position,[state] -> (ok/fail),position[]
-    // make_move,[move],[state] -> (ok/fail),state
+    let board = board::Board::new();
+    println!("{}", board.to_string());
 }