bug 3236: remove disused scripts and a function

bug 3236: remove disused scripts and a function

Removed opac/opac-dictionary.pl and catalogue/dictionary.pl,
which were not in use and not linked to from any active
template files.  According to Henri, the functionality that
these scripts implemented hasn't been working since 2.2.

Also removed C4::Search::findseealso(), which was used
only by the two scripts.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>
Signed-off-by: Henri-Damien LAURENT <henridamien.laurent@biblibre.com>