KCM Locale: Add support for Digit Grouping

Enable to the user to choose what Digit Grouping they want to use,
e.g. 123,456,789 or 12,34,56,789.  I'm not changing the defaults for
any locale as KLocale:readMoney() strictly applies the grouping so
users would suddenly find their data entry getting rejected and
wouldn't know why.

Requires kdelibs commit 7886f78

FEATURE:
FIXED-IN: 4.7.0
GUI: