Bug 28316: avoid messing up regexes in the search queries

Bug 28316: avoid messing up regexes in the search queries

This patch ensures that the behavior with
QueryRegexEscapeOptions set to values other than
"Escape" still will works as expected.

It does so by storing the contents of regexes
before escaping special characters and
then restores the contents of regexes back to how
it was before, ensuring that searching with regex is possible.

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>