D21490: Draw line caption for non-PDF documents

[Simone Gaiarin]

simgunz added a task: T11014: Dimension line annotation tool.

REPOSITORY
  R223 Okular

REVISION DETAIL
  https://phabricator.kde.org/D21490

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