Bug 8376: New script to export borrowers misc/export_borrowers.pl

Bug 8376: New script to export borrowers misc/export_borrowers.pl

This script prints to standard output what is returned by
GetMemberDetails in CSV format.
Exported fields can be specified with option -f. If no -f option is
specified, all fields are exported.

Signed-off-by: Gaetan Boisson <gaetan.boisson@biblibre.com>
Signed-off-by: Robin Sheat <robin@catalyst.net.nz>
Amended with some code to better handle bad data.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>