* Development 15 | Experimental 10 *

* Added GUIWindow
* Added GUIImageWindow
* Added GUIRendeableWindow
* Added WindowSizeChangedEvent
* Added WindowListener

* Created the package org.simplecorporation.myengine.core.gui.window
* Created the package org.simplecorporation.myengine.core.event

* Moved Event from org.simplecorporation.myengine.core.input.event to
org.simplecorporation.myengine.core.event

* Fixed bug: When changing screen size, and using OpenGL, the OpenGL
viewport wasn't resized
* Fixed bug: Problems when changing from fullscreen to not fullscreen
when using OpenGL