movements: fix 2 strings that didn't get translated
inventory.forms: let initial inhibit the "empty" selection

When calling "UnAutoCompleteField", the selector may be turned into
a ModelChoiceField. That one, however, would automatically hide the
empty "----" selection if it has an initial value. So, we make sure
that the initial is set before that.
movements: use titles in views, rather than 'object_name's

Object name can only work in English, where "Edit %(object)s" can be
a valid phrase for all %(object)s . In Greek, however, this is not
possible.
So, have full titles, that can be explicitly translated.
inventory: let "location" field label be translated
movements: split serial numbers by newlines, too
movements: they cannot have source == destination
login_middleware: expand tabs
login_middleware: after login, redirect to original request page

Suppose we wanted to see "/assets/asset/1" but are not logged-in yet.
This middleware would kick-in and redirect to "/login" . But it's
better to append the "?next=/assets/asset" so that we come back to this
page after login.

With CAS backend, this would be done with the HTTP_REFERER, which is
sometimes wrongly set.
common: fix autocomplete field in common/Location admin form
po_wizard: fix updating of serials/qty on 2nd save.

The infamous "works as you wouldn't expect" motto of Django.
Missing the po_item.save() would fail to reach the db, but /only/
in the bundle case!
movements: add the serial number in the movement items table