r766 - UI Containers

• Fixing up refreshing of textures that aren't available with other maps. (Was causing crashes)
• Adds UIContainers which can contain UI elements.
• UIContainer(x, y)
• Offset is x, y
• add(UIElement) - Adds a ui element to be rendered by this container
• addToBack(UIElement) - Adds a UI element to be rendered by this container to the back
• remove(UIElement) - Removes the UI element from rendering
• clear() - Clears everything from this container
• There is a default container called screen which everything gets added to by default
• Adds collidesWithClipBlocks to ScriptEntity
• Can retrieve the width of strings in scripts now with ui.getStringWidth
• Adds an option to center UILabels with the variable centered

Edit: Download links

With Maps - http://bit.ly/iI3aaq

No Maps - http://bit.ly/iRyEDM