Don't hard code reference formatter in tabbed view custom sorter.
Preparing release 3.2.3
Back to development: 3.2.4
Merge pull request #219 from 4teamwork/lg-reference-number-sorting

Don't hard code reference formatter in tabbed view custom sorter.
Removed IMailInAddress behavior. Not needed any more with ftw.mail 2.0.
Provide an IntIdResolver adpater to generate Dossier Mail-In addresses

based on IntIds, and use it instead of the old implementation.
Removed og.mail IMailSettings registry interface (now done in ftw.mail).

Added upgrade step to migrate settings to ftw.mail's IMailSettings and
remove old og.mail IMailSettings.
Hide standard ftw.mail mail-in viewlet (we display the mail address in the byline).