Multilanguage support for StringFormat and user input

[sevenate]

Original report by sevenate (Bitbucket: sevenate, GitHub: sevenate).

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Update internalization code to handle StringFormat and user input in binding in OS current culture format:

// Ensure the current culture passed into bindings
// is the OS culture. By default, WPF uses en-US
// as the culture, regardless of the system settings.
FrameworkElement.LanguageProperty.OverrideMetadata(
typeof (FrameworkElement),
new FrameworkPropertyMetadata(
XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));

See also: http://www.nbdtech.com/Blog/archive/2009/03/18/getting-a-wpf-application-to-pick-up-the-correct-regional.aspx
and only for silverlight: http://blogs.imeta.co.uk/jyoung/archive/2009/10/02/771.aspx (just for creating docs)