allow accepting/rejecting changes in a selection (bnc#874790)

More convenient than handling them one by one.

(cherry picked from commit 160e93607f6c2c3981823b30ee981ca23d4e1a0d)
(cherry picked from commit 4a60f9387ddd832f7c164102b76351e5e520d920)
(cherry picked from commit 94fc0b4752599601ddf9ff3c9b49da15cffb4882)
(cherry picked from commit d46e7dabd3090697c46e24a350cc75f35c28a8f7)

Change-Id: Iee02d12d595ee41cff7a31e2bda61425c9f53d6d
Reviewed-on: https://gerrit.libreoffice.org/9198
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>