Fix a refactoring-related regression that the tests missed: if
transactions were not ordered by date in the journal, register
could include postings before the report start date in the output.
We provided a very limited implementation of --display only for one use
case: to see an accurate running balance. Now that is achieved more easily
with -H/--historical, similar to the balance command, and --display
can be dropped.
As with balance. For example, register -p 'weekly in jan' generates
these intervals: 2013/12/30-2014/01/05, 2014/01/06-2014/01/12,
2014/01/13-2014/01/19, 2014/01/20-2014/01/26, 2014/01/27-2014/02/02.
With this change, postings on 2013/12/30-31 and 2014/2/1-2 will be
included in the report, so all period totals are complete and
comparable.
