Added Depth component and tidied up redundant parts of Transform

Author: photonstorm

src/gameobjects/bitmaptext/dynamic/DynamicBitmapText.js

@@ -11,6 +11,7 @@ var DynamicBitmapText = new Class({
     Mixins: [
         Components.Alpha,
         Components.BlendMode,
+        Components.Depth,
         Components.Origin,
         Components.Pipeline,
         Components.Texture,

src/gameobjects/bitmaptext/static/BitmapText.js

@@ -13,6 +13,7 @@ var BitmapText = new Class({
     Mixins: [
         Components.Alpha,
         Components.BlendMode,
+        Components.Depth,
         Components.Origin,
         Components.Pipeline,
         Components.ScaleMode,

src/gameobjects/blitter/Blitter.js

@@ -36,6 +36,7 @@ var Blitter = new Class({
     Mixins: [
         Components.Alpha,
         Components.BlendMode,
+        Components.Depth,
         Components.Pipeline,
         Components.ScaleMode,
         Components.Size,