Restore previously-open documents on launch by default
This MR implements extends Okular's existing session restoration capabilities to restore the previously-open documents when Okular is opened normally with no URLs or CLI args, not just when restoring a session. This implements in Okular the same behavior being proposed for Dolphin inhttps://phabricator.kde.org/D11382.
The feature is on by default, but can be turned off in the config file, and is only used when launching Okular with no URLs or command-line args (i.e. when it would otherwise open to a blank screen). In that sense, it can be seen as simply a more user-friendly presentation for the common case of launching Okular without a document.
TEST PLAN:
Apply this Phab patch to KXMLGui: https://phabricator.kde.org/D25106 and this Phab patch to KXMLGui: https://phabricator.kde.org/D25219
- Disable the feature: no changes in behavior
- Keep the feature on and open Okular with a document URL: Okular opens showing that document, not a saved session
- Keep the feature on and open Okular with any other command-line arguments: Okular opens and performs the action specified by the CLI arg, and does not restore a saved session
FIXED-IN: 1.10.0