Level Exit Doodad

* Add a Level Exit doodad, which for now is a little blue flag on a pole
  that reads "END"
* JavaScript API: global function EndLevel() will end the level. The
  exit doodad calls this when touched by the player.
* Add a "Level Completed" alert box UI to PlayScene with dynamic button
  layouts.
  * The alert box pops up when a doodad calls EndLevel() and contains
    action buttons what to do next.
  * "Play Again" restarts the current level again.
  * "Edit Level" if you came from the EditorScene; otherwise this button
    is not visible.
  * "Next Level" is a to-be-implemented button to advance in the single
    player story mode. Only shows up when PlayScene.HasNext=true.
  * "Exit to Menu" is always visible and closes out to the MainScene.

dev-assets/doodads/build.sh

@@ -86,7 +86,19 @@ azulians() {
 	cd ..
 }
 
+objects() {
+	cd objects/
+
+	doodad convert -t "Exit Flag" exit-flag.png exit-flag.doodad
+	doodad install-script exit-flag.js exit-flag.doodad
+
+	cp *.doodad ../../../assets/doodads/
+
+	cd ..
+}
+
 buttons
 doors
 trapdoors
 azulians
+objects

dev-assets/doodads/objects/exit-flag.js

@@ -0,0 +1,11 @@
+// Exit Flag.
+function main() {
+	console.log("%s initialized!", Self.Doodad.Title);
+	Self.SetHitbox(22+16, 16, 75-16, 86);
+
+	Events.OnCollide(function(e) {
+		if (e.InHitbox) {
+			EndLevel();
+		}
+	});
+}