[qcookboob] undo previous modif on backends, exceptions  are handled by app

At least here the player widget continued playing in the background
when closing the window with ESC, it seems it's actually only hidden.

Signed-off-by: François Revol <revol@free.fr>

Signed-off-by: François Revol <revol@free.fr>

* since there is a limited number of usable concurrent sessions
we force a logout on exit.

Signed-off-by: François Revol <revol@free.fr>

Signed-off-by: François Revol <revol@free.fr>

Diff checked manually.

autopep8 -a -ir -j2 --select=E711 .

This required the "agressive" option because it can change code
behavior.

Remove useless trailing \
Remove trailing spaces
Add missing empty lines

autopep8 -ir -j2 --select=E301,E302,E502,W291,W293,W391 .

Diff quickly checked.

autopep8 -ir -j2 --select=E303,E125
Diff checked manually.

They were not in the tools/pyflakes.sh runs

autopep8 -ir -j2 --select=W601,W602 .
Diff checked manually.