fix: Gif parsing did not work with certain formats (#3173)

Closes #3172

This PR fixes GIF parsing for certain gif formats. Leverages the documentation provided by GIFLib https://giflib.sourceforge.net/whatsinagif/index.html

## Changes:

- Tweak the image generation algorithm to be more efficient
- Support Local Color Table in image generation
- Support Disposal Method to allow frame to frame persistence

CHANGELOG.md

@@ -7,6 +7,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Breaking Changes
 
+- `ex.Gif` transparent color constructor arg is removed in favor of the built in Gif file mechanism
 - Remove core-js dependency, it is no longer necessary in modern browsers. Technically a breaking change for older browsers
 - `ex.Particle` and `ex.ParticleEmitter` now have an API that looks like modern Excalibur APIs
   * `particleSprite` is renamed to `graphic`
@@ -47,6 +48,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Deprecated
 
+
 - `Vector.size` is deprecated, use `Vector.magnitude` instead
 - `ScreenShader` v_texcoord is deprecated, use v_uv. This is changed to match the materials shader API
 - `actor.getGlobalPos()` - use `actor.globalPos` instead
@@ -55,6 +57,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- `ex.Gif` can now handle default embedded GIF frame timings
 - New `ex.Screen.worldToPagePixelRatio` API that will return the ratio between excalibur pixels and the HTML pixels. 
   * Additionally excalibur will now decorate the document root with this same value as a CSS variable `--ex-pixel-ratio`
   * Useful for scaling HTML UIs to match your game
@@ -90,6 +93,7 @@ are doing mtv adjustments during precollision.
 
 ### Fixed
 
+- Fixed issue where `ex.Gif` was not parsing certain binary formats correctly
 - Fixed issue where the boot `ex.Loader` was removing pixelRatio override
 - Fixed `ex.RasterOptions`, it now extends `ex.GraphicsOptions` which is the underlying truth
 - Fixed issue where rayCast `filter` would not be called in hit order

sandbox/tests/gif/animatedGif.ts

@@ -10,10 +10,35 @@ var game = new ex.Engine({
 
 game.currentScene.camera.zoom = 2;
 
-var gif: ex.Gif = new ex.Gif('./sword.gif', ex.Color.Black);
-var loader = new ex.Loader([gif]);
+var gif: ex.Gif = new ex.Gif('./loading-screen.gif');
+var gif2: ex.Gif = new ex.Gif('./sword.gif');
+var gif3: ex.Gif = new ex.Gif('./stoplight.gif');
+var loader = new ex.Loader([gif, gif2, gif3]);
 game.start(loader).then(() => {
-  var actor = new ex.Actor({ x: game.currentScene.camera.x, y: game.currentScene.camera.y, width: gif.width, height: gif.height });
-  actor.graphics.add(gif.toAnimation(500));
-  game.add(actor);
+  var stoplight = new ex.Actor({
+    x: game.currentScene.camera.x + 120,
+    y: game.currentScene.camera.y,
+    width: gif3.width,
+    height: gif3.height
+  });
+  stoplight.graphics.add(gif3.toAnimation());
+  game.add(stoplight);
+
+  var sword = new ex.Actor({
+    x: game.currentScene.camera.x - 120,
+    y: game.currentScene.camera.y,
+    width: gif2.width,
+    height: gif2.height
+  });
+  sword.graphics.add(gif2.toAnimation());
+  game.add(sword);
+
+  var loading = new ex.Actor({
+    x: game.currentScene.camera.x,
+    y: game.currentScene.camera.y,
+    width: gif2.width,
+    height: gif2.height
+  });
+  loading.graphics.add(gif.toAnimation());
+  game.add(loading);
 });