Refactor floating panels

• Floating panels are always big enough to fit the floating version
• they never move during animations
• when they unfloat the masks get updated so that the extra area is completely hidden
• the exclusive zone never changes and follows the unfloated geometry
• maximize window animations are better, won't resize the window twice anymore
• unfloating animation is smoother now

depends from plasma-workspace!4451 and libplasma!1148