Jobs: no need to wait for the active job to end. It actually just makes things more painful

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
JobIndexUpdater: the timeout of 1s on condition.wait() is too short, and if things go really wrong if it expires --> remove the timeout

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
JobIndexUpdater: Fix progression indication

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Main window: Make sure all the signals from jobs are handled using GObject.idle_add(). Otherwise we risk thread-safety issues with Gtk

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Main window: make sure the signals 'img-building-result-xxx' and 'page-thumbnailing-end' are never emitted twice for a same job

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Main window: don't lock the search while updating the index. There is no point

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Main window: Index update: Fix progression (again)

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Jobs: prevent multiple re-queueing of the active job

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Merge branch 'testing' into unstable

Conflicts:
	src/paperwork/frontend/mainwindow.py

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>