Merge branch 'develop' into '5732-email-backup'

# Conflicts:
#   install/sql/incremental/upd_dev_collection.sql
#   install/sql/ispconfig3.sql
#   interface/web/client/form/client.tform.php
#   interface/web/client/form/client_template.tform.php
#   interface/web/client/form/reseller.tform.php
#   interface/web/client/lib/lang/br_client.lng
#   interface/web/client/lib/lang/br_client_template.lng
#   interface/web/client/lib/lang/br_reseller.lng
#   interface/web/client/templates/client_edit_limits.htm
#   interface/web/client/templates/client_template_edit_limits.htm
#   interface/web/client/templates/reseller_edit_limits.htm