6094 Fixing ModAuthority problems

6094 Fixing ModAuthority problems

Pref MergeAuthoritiesOnUpdate does not exist; should be dontmerge
(AuthoritiesMarc.pm).

Instead of folder modified_authorities, now introducing a table for this
purpose: need_merge_authorities. This eliminates several permissions and
security issues. This change applies to AuthoritiesMarc.pm and
merge_authority.pl.

POD lines added for ModAuthority. Deprecated parameter $merge removed.

Test this patch by applying the db revision first from the second patch.

August 4, 2011: Rebased.

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Thanks Marcel. It works as advertised. Both modes are functionnal
(back):

- Immediate with dontmerge=0: After modifying an authority record, its
  linked biblios are immediately modified. This isn't the case in 3.4.5.
- Delayed with dontmerge=1: After modifying an authority record, its
  linked biblios are not modified. But an entry is added to
  need_merge_authority new table and 'merge_authorities.pl -b' script
  updates biblios.

Comment: need_merge_authority, like zebraqueue, should be cleared
from time to time.

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>