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>

2 files changed, 3 insertions, 3 deletions

diff --git a/editeng/source/items/flditem.cxx b/editeng/source/items/flditem.cxx
index 4f2c03e4b23e..11309d4a0521 100644
--- a/editeng/source/items/flditem.cxx
+++ b/editeng/source/items/flditem.cxx
@@ -396,7 +396,7 @@ void SvxDateField::Load( SvPersistStream & rStm )
 {
     sal_uInt16 nType, nFormat;
 
-    rStm.ReadUInt32( nFixDate );
+    rStm.ReadInt32( nFixDate );
     rStm.ReadUInt16( nType );
     rStm.ReadUInt16( nFormat );
 
@@ -407,7 +407,7 @@ void SvxDateField::Load( SvPersistStream & rStm )
 
 void SvxDateField::Save( SvPersistStream & rStm )
 {
-    rStm.WriteUInt32( nFixDate );
+    rStm.WriteInt32( nFixDate );
     rStm.WriteUInt16( eType );
     rStm.WriteUInt16( eFormat );
 }
diff --git a/editeng/source/uno/unofield.cxx b/editeng/source/uno/unofield.cxx
index 6a26bcddf741..5a0dddd48186 100644
--- a/editeng/source/uno/unofield.cxx
+++ b/editeng/source/uno/unofield.cxx
@@ -176,7 +176,7 @@ static SvxFileFormat setFileNameDisplayFormat( sal_Int16 nFormat )
     }
 }
 
-static util::DateTime getDate( sal_uLong nDate )
+static util::DateTime getDate( sal_Int32 nDate )
 {
     util::DateTime aDate;
     memset( &aDate, 0, sizeof( util::DateTime ) );