Add initial Map and Tile structs

src/map.rs

@@ -0,0 +1,25 @@
+use crate::prelude::*;
+
+#[derive(Clone, Copy)]
+pub enum Tile {
+    Floor,
+    Wall,
+}
+
+pub struct Map {
+    pub tiles: Vec<Tile>,
+}
+
+impl Map {
+    pub fn index(&self, x: i32, y: i32) -> usize {
+        ((y * MAP_HEIGHT) + x) as usize
+    }
+}
+
+impl Default for Map {
+    fn default() -> Self {
+        Self {
+            tiles: vec![Tile::Floor; NUM_TILES],
+        }
+    }
+}