Update guitar Tuner

Written for Guitar Tuner by lann on 2020-04-05

A new version of Guitar Tuner :
Use Gtkmm-3.0
Correct two bugs for Windows (pointer not valid and codeset in UTF-8)
Correct two bugs for Linux (problem when the the souncard is not connected and to stop the record)
Make possible the compilation in MSYS2 for windows 10 operating system