Release v2.2.1

Fixed

• When sorting cards by their backside there is no longer the chance that the hidden flag of backsides gets messed up. It may still be messed up for existing projects.
• The preview now refreshes when it is open while changing the Skip Empty Backsides setting.
• When changing the default backside it should now hide/unhide that card correctly.
• After having a backside automatically matched to its frontside we no longer keep that flag permanently, which would prevent the user from changing the backside to some other choice.
• Fixed a visual bug on Windows where the frontside of a stacked view would be hidden while hovering the backside.