Timeouts for email domain DNS check

It is no fun to wait more than 10 seconds for AgentTicketEmail or so
in the web interface
Updated jsPlumb to version 1.5.5.
Updated Russian translation, thanks to Andrey N. Burdin.
Fixed bug#10075 - Stats widgets permission group is hardcoded to 'stats'.
Updated Swedish translation, thanks to Andreas Berger.

Conflicts:
	Kernel/Language/sv.pm
Fixed wrong group names.
Revert "Fixed bug#4663 - browsing article tree by 'next / down' and 'previous / up' buttons."

This reverts commit 3e7d09ce574751490961d4b67cf25cc16b584576.

Conflicts:
	CHANGES.md
Merge branch 'dns-timeout' of https://github.com/moritz/otrs
Added a check to see if Dif'ed were installed per OPM.
Tidied.
Fixed bug#10077 - regular expressions in postmaster filter return 1 if no regex match.
Fixed: Installer fails when special characters in database user's password (bug#10056).
Fixed: Installer: error log after creating mysql database (bug#10078).
Merge remote-tracking branch 'upstream/master'