Display CPU usage on Pi Sense Hat, with a nice dot line
Using psutil to get cpu usage in percent, each second, it will display a dot base on the usage percent.
From line 0 to 7, where 0 is the upper line and equal to 100% cpu usage; and 7 the bottom line for <12.5% of cpu usage
Logically, one column equal one second (see "Anything special" below)
The brightness of the LED follows the percent value. So 100% cpu usage will be on the top line and at max bright, and low usage will be on bottom with low light.
As psutil wasn't returning a value each second request, it was displaying dots and often a space between dots, 'caused by a null value. I just had to code : "display a dot only if you have a value, so wait for it". Which is logical. Resulting in a complete dot line with no space. Wonderful.
