Properly sort track number

[erodozer]

Attempt to parse a track number into an int and sort numerically when possible.

[erodozer]

Found another case that we need to fix sorting by

[erodozer]

looks like a simple solution is just finding the number of digits of the largest number in the list and expanding the int to that length. This might not work well for large directories or recursing.

For the types of tracks with the number divided by a /, we can simply parse the whole halves and make sure the lengths match with padding.