title: How to convert a Gregorian date to an Islamic (Hijri) date?
body: <p>I know this question was asked many times but I didn't find the correct way. I have a <code>String</code> date like 01-08-1994. And I want to convert it to a <code>Hijri</code> date.
  using <code>IslamicCalendar</code>.</p>