M5Stack-SD-Updater full download & integrity check cycle

This video is boring and the music is horrible (at least I know I won't get any copyright claim ^_^), watch it a 2x speed or skip to #11:45 to see the differences between a first download, and an update check. SHA256 integrity check has been added along with some UI improvements, this makes the whole process a bit slower but prevents accidental overwriting with bogus binaries. Music: - YanCore http://play.dogmazic.net/albums.php?action=show&album=605 - Savate Powa http://play.dogmazic.net/artists.php?action=show_all_songs&artist=305