Use zero when getUserCount is unsupported. Fixes FS#2353
Improve PHPDocs and set visibility explicitly
Move strings to language files. Fix lang key
Use ->cleanUser everywhere in usermanager. Fixes FS#2849
Some auth backend have bad cleaning, but that is responsibility of these.
change visibility of private to protected
Merge pull request #348 from splitbrain/candochecksUsermanager

Cando check and localization improvements of usermanager