tdf#156449 Preserve '0' or '?' in exponent

Exponent in scientific number may use '?' as blank like in format "0.00E+?0"
This change:
- adds interpreatation of '0' and '?' in exponent
- adds "blank-exponent-digits" attribute to scientific number for import
and export to ODF
- prevents using exponent with only '?'. There must be at least one '0'
in exponent
- adds QA test of such format and test import/export/import to ODF and OOXML
- corrects one basic test

Change-Id: If52edc632a161f842270bb2fd77af535e2b978d4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154986
Tested-by: Jenkins
Reviewed-by: Laurent Balland <laurent.balland@mailo.fr>

0 files changed, 0 insertions, 0 deletions