Add max-denominator-value attibute to <number:fraction> to comply with ODF 1.3
See https://issues.oasis-open.org/browse/OFFICE-3695
Specify loext or number according to ODF version
This value is only used to stored the number of digits in numerator.
No other values than 9, 99, 999,... are expected.

Add loext:max-numerator-digits attributes to <number:fraction>
 to distinguish
??/?? and ##/## or any combination
Not saved for ODF strict
min-...-digits indicates the number of '?'
max-...-digits indicates the total number of '?' and '#'
This needs to be saved with both min-...-digits at least one
because previous versions cannot have min-...-digits of 0. See tdf#38097

Change-Id: Ibd785579aa75edc315e3bd94935a146d82bbeeef
Reviewed-on: https://gerrit.libreoffice.org/24903Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>