[SANITY CHECK NEEDED] TextFormattingMode for MetroWindow

Assuming that #889 is talking about ```MetroWindow```'s TitleBar, this *should* allow the user to set a ```TextFormattingMode``` for it's text.

Fixes #889

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Side note: If you want a history lesson, here you go: [TextOptions.TextFormattingMode affecting text with bold font weight](http://stackoverflow.com/questions/13140431/textoptions-textformattingmode-affecting-text-with-bold-font-weight)