Merge branch 'stable-3.1' of git.ispconfig.org:ispconfig/ispconfig3 into stable-3.1

interface/lib/classes/tform_base.inc.php

interface/web/admin/lib/lang/de_server_config.lng

interface/web/admin/lib/lang/en_server_config.lng

interface/web/admin/templates/system_config_domains_edit.htm

interface/web/client/templates/domain_list.htm

interface/web/dashboard/dashlets/templates/modules.htm

interface/web/dashboard/lib/lang/ar_dashlet_modules.lng

interface/web/dashboard/lib/lang/bg_dashlet_modules.lng

interface/web/dashboard/lib/lang/br_dashlet_modules.lng

interface/web/dashboard/lib/lang/ca_dashlet_modules.lng

interface/web/dashboard/lib/lang/cz_dashlet_modules.lng

interface/web/dashboard/lib/lang/de_dashlet_modules.lng

interface/web/dashboard/lib/lang/el_dashlet_modules.lng

interface/web/dashboard/lib/lang/en_dashlet_modules.lng

interface/web/dashboard/lib/lang/es_dashlet_modules.lng

interface/web/dashboard/lib/lang/fi_dashlet_modules.lng

interface/web/dashboard/lib/lang/fr_dashlet_modules.lng

interface/web/dashboard/lib/lang/hr_dashlet_modules.lng

interface/web/dashboard/lib/lang/hu_dashlet_modules.lng

interface/web/dashboard/lib/lang/id_dashlet_modules.lng