sequence filenames are not filled with leading zeros but with spaces

[joshinils]

ffmpeg fills filenames with leading zeros, when told to do so;
ffmpeg -t 00:00:01 -i INPUT.360 -map 0:0 -r 1 -q:v 1 track0/img%4d.jpg -map 0:5 -r 1 -q:v 1 track5/img%4d.jpg

max2sphere -n 1 -m 3 -o out/%d_sphere.jpg track%d/img%4d.jpg
gives the error:
CheckFrames() - Failed to open first frame "track0/img 1.jpg"

[joshinils]

the readme should also normalize the examples for the track5/DIRECTORY_%d with underscore and not.
same for the %d or %4d, which is incompatible