Wrong use of accountFromProxy()

Problem/Motivation

In the assignedLanguages() and hasPermissionForLanguage() functions there is a wrong use of the accountFromProxy(), $this->currentUser is passed instead of $account, so we got the current user languages/permissions instead of the target user languages/permissions.

Steps to reproduce

As admin:

1. Edit a user and set an allowed language
2. Save
3. Re-edit the user: the allowed language is not set because the admin permissions are loaded instead of the edited user permissions