Add IsUTC member to:

com.sun.star.util.DateTime
com.sun.star.util.DateTimeRange
com.sun.star.util.Time

Add new stucts with explicit time zones:

com.sun.star.util.DateTimeWithTimezone
com.sun.star.util.DateWithTimezone
com.sun.star.util.TimeWithTimezone

Adapt the sax::Converter to read/write timezones, and fix the unit test.

Everything else just uses default (no time zone), this commit is just
to fix the API.

STRUCT: /UCR/com/sun/star/util/DateTime
    nFields1 = 7  !=  nFields2 = 8
    Registry2 contains 1 more fields
STRUCT: /UCR/com/sun/star/util/DateTimeRange
    nFields1 = 14  !=  nFields2 = 15
    Registry2 contains 1 more fields
STRUCT: /UCR/com/sun/star/util/Time
    nFields1 = 4  !=  nFields2 = 5
    Registry2 contains 1 more fields

Conflicts:
	sc/source/filter/oox/unitconverter.cxx

Change-Id: I01f7a6d082a6b090c8efe71d2de137474c495c18
Reviewed-on: https://gerrit.libreoffice.org/4833Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>