Merge remote branch 'kc/master' into new/enh/bug_5917

Conflicts:
	installer/data/mysql/en/mandatory/sysprefs.sql

diff --cc C4/Auth.pm
Simple merge

diff --cc installer/data/mysql/fr-FR/1-Obligatoire/unimarc_standard_systemprefs.sql
Simple merge

diff --cc installer/data/mysql/pl-PL/mandatory/sysprefs.sql
Simple merge

diff --cc installer/data/mysql/ru-RU/mandatory/system_preferences_full_optimal_for_install_only.sql
Simple merge

diff --cc koha-tmpl/opac-tmpl/prog/en/includes/doc-head-close.inc
Simple merge