There is the Problem error, like you can see It is new for me :
Arduino: 1.8.6 Hourly Build 2018/01/03 03:33 (Windows 10), Board: "Arduino/Genuino Uno"
C:\Users\Ian Patry\Documents\Arduino\AS3935 lightning sensor with an Arduino\PWFusion_AS3935_SPI-master\Examples\as3935_lightning_snsr_nocal\as3935_lightning_snsr_nocal.ino:69:29: fatal error: PWFusion_AS3935.h: No such file or directory
#include "PWFusion_AS3935.h"
^
compilation terminated.
exit status 1
Error compiling for board Arduino/Genuino Uno.
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.