Some dragging and wraparound fixes!

• #582 Another attempt to fix the height issue by changing the default prop value for height
• #584 Fix multi-slide wraparound (Thanks @dbangerter2!)
• #585 Fix onDragStart, should only happen with dragging/swiping (Thanks @jflayhart!)
• #588 Impossible to select last images when swiping, this fixes that (Thanks @gonzadk!)