Resolves: tdf#100452 class Date full (BCE,CE) proleptic Gregorian calendar

... implementing signed years with year 0 gap.
Date(31,12,-1) last day BCE
Date(1,1,1) first day CE

New class Date member functions:
* AddYears(sal_Int16) to be used instead of
  aDate.SetYear(aDate.GetYear()+sal_Int16) to handle year 0 gap.
* convenience GetNextYear() to be used insted of GetYear()+1
* convenience GetPrevYear() to be used insted of GetYear()-1
* AddMonths(sal_Int32)
* operator=(const css::util::Date&)

New class DateTime member functions:
* operator=(const css::util::DateTime&)

Made some conversion ctors explicit, specifically Date(sal_Int32)

Adapted hopefully all places that used a sal_uInt16 year to use
sal_Int16 where appropriate.

Eliminated some quirks in date handling found on the fly.

Added era handling to i18npool icu calendar setting interface, which
missing was responsible for 0001-01-01 entered in Calc being set as
-0001-01-01, hence subtracting one day resulted in -0002-12-31.

Change-Id: I77b39fba9599ebd5067d7864f6c9ebe01f6f578f
Reviewed-on: https://gerrit.libreoffice.org/27049
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/basic/source/runtime/methods.cxx b/basic/source/runtime/methods.cxx
index 296af1514bcd..2abca341ca68 100644
--- a/basic/source/runtime/methods.cxx
+++ b/basic/source/runtime/methods.cxx
@@ -4858,7 +4858,7 @@ sal_Int16 implGetDateYear( double aDate )
     long nDays = (long) aDate;
     nDays -= 2; // standardize: 1.1.1900 => 0.0
     aRefDate += nDays;
-    sal_Int16 nRet = (sal_Int16)( aRefDate.GetYear() );
+    sal_Int16 nRet = aRefDate.GetYear();
     return nRet;
 }
 
@@ -4917,7 +4917,7 @@ bool implDateSerial( sal_Int16 nYear, sal_Int16 nMonth, sal_Int16 nDay, double&
             {
                 nYearAdj = ( ( nMonth -12 ) / 12 );
             }
-            aCurDate.SetYear( aCurDate.GetYear() + nYearAdj );
+            aCurDate.AddYears( nYearAdj );
         }
 
         // adjust day value,