model: add mutable MapState (empty for now)

src/model/data/MapData.ts

@@ -0,0 +1,25 @@
+import {mapFromObject} from '../../util';
+
+interface Input {
+	readonly tiles: {[key: string]: string};
+	readonly collision: string[];
+	readonly layers: string[][][];
+}
+
+export default class MapData {
+	public readonly tiles: Map<string, string>;
+	public readonly collision: string[];
+	public readonly layers: string[][][];
+
+	public readonly width: number;
+	public readonly height: number;
+
+	constructor(data: Input) {
+		this.tiles = mapFromObject(data.tiles);
+		this.collision = data.collision;
+		this.layers = data.layers;
+
+		this.height = this.collision.length;
+		this.width = this.collision[0].length;
+	}
+}