Use threads

[bilelmoussaoui]

In order to improve the speed of the script, and as we moved to a more OOP code. I think it's might be cool that each application has its own thread that will fix it icons and kill itself after that.

[bilelmoussaoui]

On master, here's the difference before threads and after :p
before :
sudo -E python3 script.py 37,13s user 7,43s system 220% cpu 20,227 total
after :
sudo -E python3 script.py 0,83s user 0,07s system 46% cpu 1,945 total
And here's a list of the applications that was fixed

Caprine             [###.....................................] 6/70 8.6%
Chromium            [####....................................] 7/70 10.0%
Dropbox             [#######.................................] 13/70 18.6%
Google Chrome       [########................................] 14/70 20.0%
Megasync            [##########..............................] 18/70 25.7%
Skype               [###########################.............] 48/70 68.6%
Spotify             [#################################.......] 57/70 81.4%
Steam               [#################################.......] 58/70 82.9%
Stremio             [##################################......] 59/70 84.3%
Teamviewer          [#####################################...] 65/70 92.9%
Telegram            [#######################################.] 68/70 97.1%
Wire                [########################################] 70/70 100.0%

@varlesh you might want to give this a try :p

[bilelmoussaoui]

Removed the threads for now! it causes too many issues (the threads were used as daemons, and they are killed once the script is done, which causes too many problems with the execution of the script..).
I don't have any idea how to get this done for now.