Merge remote-tracking branch 'origin/gui'
[master] Add main module.
[gui] Add error popup message when an error occurs during excel export
of a report.
[gui] Add error popup in the gui when the generation of the report is
impossible.
[gui] Uncaught exceptions are caught at the application level, cause an
error popup to appear and close the application. Already existing popups
are improved with the traceback available in the details section.