add `bitsy-dedupe` executable

src/bin/bitsy-dedupe.rs

@@ -0,0 +1,16 @@
+extern crate bitsy_parser;
+use bitsy_parser::game::Game;
+use std::{env, fs};
+
+const SYNTAX_ERROR: &str = "No game data specified. Usage: `bitsy-dedupe input.bitsy output.bitsy`";
+
+fn main() {
+    let game   = env::args().nth(1).expect(SYNTAX_ERROR);
+    let output = env::args().nth(2).expect(SYNTAX_ERROR);
+
+    let mut game = Game::from(fs::read_to_string(game).unwrap()).unwrap();
+
+    game.dedupe_tiles();
+
+    fs::write(output, game.to_string()).expect("Failed to write output file");
+}