Added a check to see if Dif'ed were installed per OPM.
Updated jsPlumb to version 1.5.5.
Updated Russian translation, thanks to Andrey N. Burdin.
Updated Swedish translation, thanks to Andreas Berger.
Fixed bug#10075 - Stats widgets permission group is hardcoded to 'stats'.

Conflicts:
	CHANGES.md
Fixed wrong group names.
Merge branch 'feature-checksumImpovement-shb-master' of https://github.com/dignin/otrs into rel-3_3
Tidied.
Fixed bug#10077 - regular expressions in postmaster filter return 1 if no regex match.
Fixed CHANGES.
Fixed: Installer fails when special characters in database user's password (bug#10056).
Extended fix for bug#9928 - Dropdown field in tree mode are not displayed in tree mode in column filters.
Fixed: Installer: error log after creating mysql database (bug#10078).