Bug 24674: Uncertain years for publicationyear/copyrightdate -- corrected

Bug 24674: Uncertain years for publicationyear/copyrightdate -- corrected

This is a correction to Bug 11046: YYY-, YY--, Y---, are also
correct according to ISBD: uncertain year, but certain decade/century
(cf. n. 4.3.8 in ISBD Consolidated Edition of 2011).
(Question mark is not mandatory.)

In addition, in Poland a form with one only dash is quite common,
like YY- (== YY--).

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
See last follow-up.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>