Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style

Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style

-) Foreground AccentSelectedColorBrush when selected
-) Background AccentBrush when selected
-) Background AccentColor3 when mouseover
Fixed the vertical alignment of the WindowsCommands

If the maximize, minimize and close buttons were hidden, the vertical
alignment of the WindowCommands was not centered
Merge pull request #463 from flagbug/windowcommands-fix

Fixed the vertical alignment of the WindowsCommands
Merge pull request #450 from stefan-schweiger/patch-3

Changed ComboBox Selection Style to better fit ListBox, ListView, etc. style
Nuke strange things, integrate the icons window
Overrode the ListView's original template to enable styling of the Disabled state.
Added a context menu sample
Bigger headings
Merge pull request #464 from flagbug/demo-overhaul

MetroDemo overhaul
DatePicker
MetroCalendar - Default style
MetroCalendar - AccentColor and DefaultStyle
DatePicker - TextboxHelper.Watermark

TextboxHelper.Watermark  will override DatePickers internal Watermark,
which is less flexible...

Not working at designtime for some reason :-/
DatePicker - changed popup alignment

Previously aligned to internal textbox, which made the popup overlapp
the border.
Calendar - BlackBrush border to match textbox
added tab into demo app
Adapt the ListViews disabled state to the ListBox disabled state
Merge pull request #468 from MahApps/listview-disabled-style

Adapt the ListViews disabled state to the ListBox disabled state
just get out of my way you silly artifacts
ComboBox virtualizing is disabled
If a control of type ItemsPresenter is used as item presenter, then the virtualization of the ComboBox is being disabled. Use VirutalizingStackPanel instead and set the property IsItemsHost to true.

Conflicts:
	MahApps.Metro/Styles/Controls.ComboBox.xaml