fix possible null pointer exception
add missing MetroAnimatedTabControl to generic
improved TabControl demos
DependentUpon
use nearly same styles
Merge branch 'origin/master' #680

Conflicts:
	samples/MetroDemo/MainWindow.xaml
revert #680 from xxMUROxx/hotfix/FontSizeProperty-TabItem

Removed HeaderFontSize-DP and used FontSize-DP in TabItem
need this for #739  (reverted from commit 10326e7f480155bfd9903a4cff31d69612d89814)

this breaks the inner FontSize!!!
close button can be null
introduce TabItemFontSize
no CheckForMainResourceDictionaries
first try for controls at app.xaml

changing theme with the theme manager doesn't work (must be
re-implemented)
fix textblock issue with controls at app.xaml
fix groupbox header foreground color
fix window title foreground
re-use MetroTextBlock
update AccentColorRepro
minor to caliburn demo
remove commented code
InheritAccentColorsAndTheme is now obsolete
better style format