Bug 21959: Batch item modification - ability to apply regular expression on text...

Bug 21959: Batch item modification - ability to apply regular expression on text fields

Test plan:
  - go to Tools > Batch item modification,
  - select items to modify,
  - for one or some text fields, check the second checkbox (Use regular
    expression) and type your regex,
  - check the regex has been applied.

Signed-off-by: Pierre-Marc Thibault <pierre-marc.thibault@inLibro.com>
Signed-off-by: Mathilde Formery <mathilde.formery@ville-nimes.fr>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>