Improvements

[punker76]

• [x] enable/disable title bar (change title bar height)
• [x] enable/disable drop shadow
• [x] override title bar background and content background, also foreground and font stuff
• [x] title bar icon
• [x] close button
• [x] enable contenttemplate
• [x] simple child window moving
• [x] simple child window manager to show window the async way