Minor improvements to WFCDemo usability.

You can randomize the state by pressing r; pressing PrintScreen won't change the map state so you can take a picture of it. The README.md includes examples and controls.

WFCDemo/README.md

@@ -0,0 +1,17 @@
+# WFC Demo using Tiled
+
+## Controls
+
+They're simple! Press `q` or `Esc` to exit. Press `r` to randomize the map.
+Press `PrintScreen` to do nothing and let the OS handle taking a screenshot.
+Press any other key to generate the next map in order.
+
+This starts with a fixed seed so the first result will always be the same.
+Unless you press `r`, other maps generated will follow a specific order,
+the same every time. Pressing `r` will randomize and generate the next map.
+
+## Examples
+
+![Example generated map](https://i.imgur.com/7Q1gYyl.png)
+
+![Example generated map](https://i.imgur.com/KGtiV9V.png)

WFCDemo/core/src/main/java/com/squidpony/demo/WFCDemo.java

@@ -8,6 +8,7 @@
 import com.badlogic.gdx.maps.tiled.TiledMapTileLayer;
 import com.badlogic.gdx.maps.tiled.TmxMapLoader;
 import com.badlogic.gdx.maps.tiled.renderers.OrthogonalTiledMapRenderer;
+import com.badlogic.gdx.utils.NumberUtils;
 import jagd.MimicWFC;
 import jagd.RNG;
 
@@ -60,6 +61,13 @@ public boolean keyUp(int keycode) {
                     case Input.Keys.ESCAPE:
                         Gdx.app.exit();
                         break;
+                    case Input.Keys.PRINT_SCREEN:
+                        System.out.println("Printing screen.");
+                        break;
+                    case Input.Keys.R:
+                        System.out.println("Now using initial state " +
+                                (rng.state = NumberUtils.doubleToLongBits(Math.random()) ^ NumberUtils.doubleToLongBits(Math.random()) >>> 32));
+                        // FALLTHROUGH
                     default:
                         remake();
                         renderer.setMap(tiledMap);