neuland-window.c: Fix indentation
window: Fix the _get_property function

This was a copy and paste from the _set_property part
neuland-contact-row.ui: Remove deprecated props

Glade still keeps adding them back.
window: Some selection improvements

Now accepting/deleting can only be done when in selection mode, because
it seems to be clearer. This means the Discard/Accept buttons no longer
show up in the header bar. This commit also disables/enables some
actions when toggling the selection mode.
welcome widget: Set the expand property to TRUE

Otherwise the widget doesn't show up centered.
tox: Actually do finalize contacts when deleting

The key of the priv->contacts_ht uses the contact's number, not the
address.