New option to blink background pictures of jobs when building

Hi @pellepeister,

I made a new feature to be able to blink background pictures of jobs being built.

You can test this feature by yourself. It's without bug. 

I fixed by the same way an issue on the paintInterval config (the update was not working).
You have to set the paintInterval at least to 1 (preferably more).

You can enable/disable it with an option in the config. The display of jobs without this option is still working.

Regards,
@libetl (Lionel)