Changed MetroDialogOptions to a DependencyProperty
Removed duplicate DependencyProperty definition.
Click on Expander header support
Merge pull request #1291 from Dotnetifier/patch-1

Click on Expander header support
Merge pull request #1289 from xxMUROxx/hotfix/Make_MetroDialogOptions_DependencyProperty

Changed MetroDialogOptions to a DependencyProperty