New islamic calendar

New Features

• Create an experimental version of Umalqura calendar [#313]
• Start-of-day-feature, relevant for current date in islamic calendar [#323]
• New pattern type for generic date chronologies [#324]
• New transformation methods for calendrical objects [#318]

Deprecations

• Interface ExtZoneProvider no longer used

Incompatibilities

• Narrow value-type of BasicElement to Comparable [#321]