Add islamic calendar (including Umalqura)

[MenoData]

Basic idea is to realize the calendar as table-driven implementation with an extra ChronoExtension deploying various algorithms for a calculatory view.

[MenoData]

Some links:

http://www.ummulqura.org.sa/index.aspx (authoritative reference) http://www.staff.science.uu.nl/~gent0113/islam/ummalqura.htm (outdated data from early 90ies) http://stackoverflow.com/questions/13016365/java-library-for-hijri-umm-al-qura-calendar http://stackoverflow.com/questions/15728744/converting-gregorian-to-hijri-date https://github.com/msarhan/ummalqura-calendar (based on java.util.Calendar and old data) http://code.google.com/p/hijricalendar/source/browse/trunk/HijriCalendar/src/#src%2FastroLib

https://en.wikipedia.org/wiki/Islamic_calendar https://en.wikipedia.org/wiki/Tabular_Islamic_calendar

http://www.staff.science.uu.nl/~gent0113/islam/islam_tabcal.htm http://www.joda.org/joda-time/cal_islamic.html http://stackoverflow.com/questions/30758399/joda-api-not-return-proper-islamic-date http://stackoverflow.com/questions/28693959/conversion-from-gregorian-to-hijri-islamic-date-in-pakistan

http://www.staff.science.uu.nl/~gent0113/islam/diyanetcalendar.htm (turkish variant)

Two useful links how ICU-implementation works: http://source.icu-project.org/repos/icu/icu4j/tags/release-55-1-localespi-java8-20150610/main/classes/core/src/com/ibm/icu/util/IslamicCalendar.java http://source.icu-project.org/repos/icu/icu4j/tags/release-55-1-localespi-java8-20150610/main/classes/core/src/com/ibm/icu/impl/CalendarAstronomer.java

[MenoData]

With release 3.9/4.6, this issue is solved - see also #362.