Level Difficulty + UI Polish

Added a new level property: Difficulty

* An enum ranging from -1, 0, 1 (Peaceful, Normal, Hard)
* Default difficulty is Normal; pre-existing levels are Normal by
  default per the zero value.

Doodad scripts can read the difficulty via the new global variable
`Level.Difficulty` and some doodads have been updated:

* Azulians: on Peaceful they ignore all player characters, and on Hard
  they are in "hunt mode": infinite aggro radius and they're aggressive
  to all characters.
* Bird: on Peaceful they will not dive and attack any player character.

Other spit and polish:

* New Level/Level Properties UI reworked into a magicform.
* New "PromptPre(question, answer, func)" function for prompting the
  user with the developer shell, but pre-filling in an answer for them
  to either post or edit.
* magicform has a PromptUser field option for simple Text/Int fields
  which present as buttons, so magicform can prompt and update the
  variable itself.
* Don't show the _autosave.doodad in the Doodad Dropper window.

dev-assets/doodads/azulian/azulian.js

@@ -18,8 +18,8 @@ if (color === 'white') {
 }
 
 function setupAnimations(color) {
-	let left = color === 'blue' ? 'blu-wl' : color+'-wl',
-		right = color === 'blue' ? 'blu-wr' : color+'-wr',
+	let left = color === 'blue' ? 'blu-wl' : color + '-wl',
+		right = color === 'blue' ? 'blu-wr' : color + '-wr',
 		leftFrames = [left + '1', left + '2', left + '3', left + '4'],
 		rightFrames = [right + '1', right + '2', right + '3', right + '4'];
 
@@ -71,7 +71,8 @@ function main() {
 				myPt = Self.Position();
 
 			// If the player is within aggro range, move towards.
-			if (Math.abs(playerPt.X - myPt.X) < aggroX && Math.abs(playerPt.Y - myPt.Y) < aggroY) {
+			if ((Math.abs(playerPt.X - myPt.X) < aggroX && Math.abs(playerPt.Y - myPt.Y) < aggroY)
+				|| (Level.Difficulty > 0)) {
 				direction = playerPt.X < myPt.X ? "left" : "right";
 				followPlayer = true;
 
@@ -134,11 +135,16 @@ function playerControls() {
 // will be hostile towards the player). Boring players will not be chased after and
 // the Azulian will not harm them if they make contact.
 function isPlayerFood(actor) {
-	// Not a player or is invulnerable.
-	if (!actor.IsPlayer() || actor.Invulnerable()) {
+	// Not a player or is invulnerable, or Peaceful difficulty.
+	if (!actor.IsPlayer() || actor.Invulnerable() || Level.Difficulty < 0) {
 		return false;
 	}
 
+	// On hard mode they are hostile to any player.
+	if (Level.Difficulty > 0) {
+		return true;
+	}
+
 	// Azulians are friendly to Thieves and other Azulians.
 	if (actor.Doodad().Filename === "thief.doodad" || actor.Doodad().Title.indexOf("Azulian") > -1) {
 		return false;

dev-assets/doodads/bird/bird.js

@@ -1,8 +1,8 @@
 // Bird
 
 let speed = 4,
-		Vx = Vy = 0,
-		altitude = Self.Position().Y; // original height in the level
+	Vx = Vy = 0,
+	altitude = Self.Position().Y; // original height in the level
 
 let direction = "left",
 	lastDirection = "left";
@@ -72,7 +72,7 @@ function main() {
 			// Scan for the player character and dive.
 			try {
 				AI_ScanForPlayer()
-			} catch(e) {
+			} catch (e) {
 				console.error("Error in AI_ScanForPlayer: %s", e);
 			}
 		}
@@ -84,7 +84,7 @@ function main() {
 
 		// If diving, exit - don't edit animation.
 		if (state === states.diving) {
-			Self.ShowLayerNamed("dive-"+direction);
+			Self.ShowLayerNamed("dive-" + direction);
 			lastDirection = direction;
 			return;
 		}
@@ -109,6 +109,11 @@ function main() {
 // It's not hostile towards characters that can fly (having
 // no gravity).
 function AI_ScanForPlayer() {
+	// If Peaceful difficulty, do not attack.
+	if (Level.Difficulty < 0) {
+		return
+	}
+
 	let stepY = 12, // number of pixels to skip
 		stepX = stepY,
 		limit = stepX * 20, // furthest we'll scan
@@ -153,14 +158,14 @@ function player() {
 	// they aren't seen to be moving downwards, cancel the dive.
 	let lastPoint = Self.Position();
 	setInterval(() => {
-        let nowAt = Self.Position();
-        if (nowAt.Y > lastPoint.Y) {
-            falling = true;
-        } else {
-            falling = false;
-        }
-        lastPoint = nowAt;
-    }, 100);
+		let nowAt = Self.Position();
+		if (nowAt.Y > lastPoint.Y) {
+			falling = true;
+		} else {
+			falling = false;
+		}
+		lastPoint = nowAt;
+	}, 100);
 
 	Events.OnKeypress((ev) => {
 		Vx = 0;
@@ -198,7 +203,7 @@ function player() {
 		} else {
 			// Hover in place.
 			if (!Self.IsAnimating()) {
-				Self.PlayAnimation("fly-"+direction);
+				Self.PlayAnimation("fly-" + direction);
 			}
 			diving = false;
 		}