- moved rendering of antialiased corners from Oxygen::ShadowCache to Oxygen::Client.
- simplified caching of ShadowCache accordingly. Notably, it should make it easier to pass the shadows to kwin.
- removed unnecessary QPainter::save()/restore() calls
- set painter AntiAliasing render hint earlier in Client::paintEvent
- modified drawing of drop target rect accordingly.
- oh. And fixed krazy warnings.