Details of the client content type changes in 1.0-rc3

To complement the release notes, issue #962330 and freeze exception discussions, here's documentation of the significant client content type changes in 1.0-rc3. The whole spirit of this change is to make the client more like a UNIX group than a separate entity, so a lot of information that was duplicated from the Drupal user is now gone from the content type. This is part of an overall effort to improve security in Aegir.

Spcifically, the organisation and email fields were dropped from the form, and the "name" field was dropped in favor of the node title. An "internal name" column was added, autocalculated from the node title. We move from email being unique to the internal name being unique, which also resolves client duplication issues. The internal name is designed to be usable as the UNIX group name.

The name, email and organisation fields will not be explicitely removed from the DB until 2.x, but they are not created anymore on install. This is to make migrations from previous database structures easy to fix if the builtin upgrade script doesn't behave the way you like. All this work was part of issue #962330.

Since the client doesn't have an email anymore, site creation emails get sent to the logged in user instead of the client email (issue #336068).

From the API side, the hosting_get_client_by_email() function was deprecated and now yields an ugly warning.