Add create_map()

src/main.rs

@@ -9,6 +9,13 @@ struct World {
     map: Vec<char>,
 }
 
+impl World {
+    /// Create a new map full of dots.
+    fn create_map(&mut self) {
+        self.map = vec!['.'; (self.x * self.y) as usize];
+    }
+}
+
 /// Struct to store robot position.
 struct Position {
     x: u32,
@@ -112,6 +119,7 @@ fn open_file(filename: &str) -> io::Result<String> {
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // We handle CLI flags here.
     let matches = App::new("DancingDroids")
         .version("0.1.0")
         .about("When droids dance togethers")