refreshing glass frame

with this change it is possible to get a maximized window with hidden taskbar.
so we can set initial ```GlassFrameThickness = new Thickness(0)``` with ```WindowStyle=None``` to get a custom window.
now if user maximize the window we can set ```GlassFrameThickness = new Thickness(1)``` to get a window that fills the complete monitor and hides the taskbar (this should happened in maximized event of the window).
with ```GlassFrameThickness = new Thickness(0)``` we can set back to a custom styled window without showing the glass frame.
this all works only with ```WindowStyle=None```!

i hope this brakes nothing :-D

Closes #5