Bug 10380: Change prototype for output_pref() routine

Koha::DateUtils::output_pref took 4 parameters and the last one is a
boolean, so some calls were:
  output_pref($dt, undef, undef, 1)

This patch changes its prototype to
  output_pref({
    dt => $dt,
    dateformat => $dateformat,
    timeformat => $timeformat,
    dateonly => $boolean
  });

An alternative is to call the output_pref routine with a datetime
object, without using an hashref:

  output_pref($dt);

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10380: (follow-up) update some uses of output_pref()

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10380: (follow-up) update two more uses of output_pref()

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10380: (follow-up) update POD to fully reflect change to output_pref()

Signed-off-by: Galen Charlton <gmc@esilibrary.com>