Don't munge from header when restoring composer from a draft. Bug 768419.
Don't munge from header when restoring composer from a draft. Bug 768419.

* src/client/composer/composer-widget.vala
  (ComposerWidget::ComposerWidget): Set the from property for
  ComposeType.NEW_MESSAGE when the referred email is not null - i.e. it's
  a draft, call ::update_from_field afterwards so that is taken into
  account.
  (ComposerWidget::add_recipients_and_ids): Merge body of
  ::set_preferred_from_address here since it's the only call site, update
  that to only munge the from property only if not composing a new email
  - i.e. a draft, so that ::restore_draft_state_async does not clobber it
  when calling this method with referred messages that aren't the draft.

mjog/geary,tshikaboom/geary,tshikaboom/geary,mjog/geary,mjog/geary,tshikaboom/geary