Bug 26569: Use gender neutral pronouns in system prefernece explanations

Bug 26569: Use gender neutral pronouns in system prefernece explanations

To test:
1 - perform query "select variable,explanation from systempreferences where explanation like '% his %';"
2 - find 6 sysprefs with gendered pronouns used in explanations
3 - apply patch, reset_all
4 - repeat query
5 - no more gendered pronouns!

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit a96f5deef04bb74fbd826449b4d82f651a67512c)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 9de5ceeaec33f6f26fb2dfefbfd1fb6414ed9b90)

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>
(cherry picked from commit f48c2578e87641aaab2826c84ba396ae83bf64ad)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>