Don't link to QtXml; we don't actually use any classes from this module.

QXmlStream* classes are in QtCore.
Add radial gradient object
Register margin and padding property on HSSDisplayObject
Handle `yes` and `no` keywords for 'contained' property of display objects
Fix ref(content of <selector>)
Fix ref(shape of <selector>)
Fix refs to numeric properties of HSSContainer
Fix ref(contained of <selector>)
Fix ref(font of <selector>)
Fix ref(on of <selector>)
Fix ref(margin of <selector>)
Fix ref(padding of <selector>)
Fix ref(border of <selector>)
Fix ref(visible of <selector>)
Observe the height instead of the width in anchorY
Return correct value in getDContentAlignY()
Refactor the AXR rendering code.
Add HSSRenderTreeBuilder.
Update AUTHORS.
Minor code style fixes/refactoring related to recent rendering changes.