Fix recent action menu (Qt5 porting bug)
The usage of the text field is fragile, as the accelerator is dynamically
added. Add a marker and the URLs of opened repositories inside the data
field of the QAction.
This fixes two porting issues:
- population of the recent menu (upon opening a new repository, the
initial entries were kept as they started with & instead of a cypher);
- click on a recent entry (the initial cypher was not found due to the &
and no repository was opened).