No longer allow layer and panel as top level elements. Create a screenElementType which just has the attributes necessary for the screen. Add a "type" attribute to control and make it required. Create "typeType" for controls and limit choices to what is supported.
Add skeleton builder classes for creating GUIs.
Add skeleton widget classes for GUIs.
Schema now is able to handle multiple locations of default attributes from the XSD. GuiElement.java and GuiImageElement.java was renamed and moved to the widget package.
Remove GuiElement from the factory.
loadXml in ClumsyGui is validating the XML file, parsing and extracting default attributes from the XSD. Then the GuiScreens are being created and initialized from the XML elements. The initialization is not yet implemented.