update of 8/2018

an install of cpufrequtils is now also required on standard Ubuntu or Mint 
19 installations. 

This will do the trick:

sudo apt install cpufrequtils

so for compiling and running all that's required is an:

sudo apt install build-essential xprintidle cpufrequtils

and for proper execution an editing of the *.run frequency profiles that's 
appropriate to your hardware.