titlebar enhancements

some titlebar enhancments

- [x] vector icon support (template support)
- [x] left window commands
- [x] title templating
- [x] style minimize/maximize/close buttons
- [x] Fix ShowIconOnTitleBar=true + TitlebarHeight=0 #1124 #1125 ( @100GPing100 ) - Fixes #1124 
- [x] changing clean demo style
- [x] handle ShowWindowCommandsOnTop for left commands (maybe we should see the icon too...)
- [x] icon on top if ShowWindowCommandsOnTop = true
- [x] rename WindowCommands -> RightWindowCommands (and mark WindowCommands as obsolete)

![2014-03-09_19h15_22](https://f.cloud.github.com/assets/658431/2368678/0c115378-a7b7-11e3-9732-5a9daf9c0825.png)

![2014-03-08_00h55_43](https://f.cloud.github.com/assets/658431/2363749/181c2170-a654-11e3-86da-d79f2b5c1c3b.png)

![2014-03-06_21h58_55](https://f.cloud.github.com/assets/658431/2350612/715bd272-a572-11e3-91e6-71658f58b95a.png)
```xml
<Controls:MetroWindow.LeftWindowCommands>
    <Controls:WindowCommands>
        <Button Click="LaunchMahAppsOnGitHub"
                ToolTip="MahApps.Metro on GitHub">
            <Rectangle Width="22"
                       Height="22" Fill="{DynamicResource WhiteBrush}">
                <Rectangle.OpacityMask>
                    <VisualBrush Stretch="Uniform"
                                 Visual="{StaticResource appbar_github}" />
                </Rectangle.OpacityMask>
            </Rectangle>
        </Button>
    </Controls:WindowCommands>
</Controls:MetroWindow.LeftWindowCommands>
```

![2014-03-04_13h51_27](https://f.cloud.github.com/assets/658431/2321123/9951e4c4-a39c-11e3-9cb5-58b6cd285668.png)
```xml
<Controls:MetroWindow.IconTemplate>
    <DataTemplate>
        <Grid Width="{TemplateBinding Width}"
              Height="{TemplateBinding Height}"
              Margin="4"
              Background="{DynamicResource WhiteBrush}"
              RenderOptions.EdgeMode="Aliased"
              RenderOptions.BitmapScalingMode="HighQuality">
            <Grid.OpacityMask>
                <VisualBrush Stretch="Uniform"
                             Visual="{DynamicResource appbar_box}" />
            </Grid.OpacityMask>
        </Grid>
    </DataTemplate>
</Controls:MetroWindow.IconTemplate>
```

![2014-03-04_21h44_06](https://f.cloud.github.com/assets/658431/2326122/a33d9a04-a3de-11e3-9267-1c7bfc2ffd4e.png)
```xml
<Controls:MetroWindow.TitleTemplate>
    <DataTemplate>
        <TextBlock Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content, Converter={StaticResource ToUpperConverter}}"
                   TextTrimming="CharacterEllipsis"
                   HorizontalAlignment="Right"
                   VerticalAlignment="Center"
                   Margin="0 -1 8 0"
                   FontSize="{DynamicResource WindowTitleFontSize}"
                   FontFamily="{DynamicResource HeaderFontFamily}" />
    </DataTemplate>
</Controls:MetroWindow.TitleTemplate>
```