Implemented the mount interface, Fixed some interface stuff, Some cosmetics, and Updated the outfits window

* Added new arrow buttons.
* Fixed the vertical separator.
* Added new game_playermount module to handle player mounting.
* Moved the battle icons to /images.
* Outfit window accommodates for mounts, loads addons more efficiently and keeps addons set on update, added new Outfit.randomize function that allows you to randomize your outfit colors, and set up a new layout.

modules/client_skins/skins/default/styles/buttons.otui

@@ -38,4 +38,4 @@ TabButton < UIButton
 
   $on:
     image-clip: 0 40 20 20
-    color: #80c7f8
+    color: #80c7f8

modules/client_skins/skins/default/styles/separators.otui

@@ -6,7 +6,7 @@ HorizontalSeparator < UIWidget
   focusable: false
 
 VerticalSeparator < UIWidget
-  image-source: /images/horizontal_separator.png
+  image-source: /images/vertical_separator.png
   image-border-left: 2
   width: 2
   phantom: true