Bug 4838 Allow to choose which authority heading to copy into biblio record

Bug 4838 Allow to choose which authority heading to copy into biblio record

With this patch, in biblio record data entry form, when ... is clicked for an
authority controlled field, it's possible to select which heading repetion to
copy if the authority has repeated headings.

When there is just one authority repetition, the first one is displayed to
choose, as previously.

This patch is REQUIRED by French libraries following SUDOC UNIMARC format, and
cataloguing multilingual materials ie all Higher Educational and Research
libraries.

Signed-off-by: Henri-Damien LAURENT <henridamien.laurent@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>