Add QCalendarBackend as a base class for calendar implementations and
QCalendar as a facade via which to access it.
QDate's implicit implementation of the Gregorian calendar becomes
QGregorianCalendar and QDate methods now support choice of calendar.
Convert QLocale's CLDR data for month names to a locale-data component
of each supported calendar and relevant QLocale methods now support
choice of calendar. Adapt Python scripts for locale data generation to
extract month name data from CLDR (keeping on version v35.1) into the
new calendar-locale files. The locale data for the Gregorian calendar
is held in a Roman calendar base, for sharing with other calendars.
Add tests for basic uses of the new API.
[ChangeLog][QtCore][QCalendar] Added QCalendar to support diverse
calendars, supported by implementing QCalendarBackend.
[ChangeLog][QtCore][QDate] Allow choice of calendar in various
operations, with Gregorian remaining the default.
Done-with: Lars Knoll <lars.knoll@qt.io>
Done-with: Edward Welbourne <edward.welbourne@qt.io>
Fixes: QTBUG-17110
Fixes: QTBUG-950
Change-Id: I9d6278f394269a183aee8156e990cec4d5198ab8
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
aa8393c94f