D18283: Auto-expand all tree elements in the side panel when the panel is first shown

[Simone Gaiarin]

simgunz added a task: T8553: Improve review side panel.

REPOSITORY
  R223 Okular

REVISION DETAIL
  https://phabricator.kde.org/D18283

To: joaonetto
Cc: simgunz, aacid, okular-devel, tfella, ngraham, darcyshen