Supports # as separator for groups

This is because Windows barfs when exporting filenames with : in them.
Revert "Supports # as separator for groups"

This reverts commit 22e11ed4c061c7c35d74a83c3be0f1183340810d.
Support # as separator for groups

This is because Windows doesn't like : in filenames.

Closes #90
Use new separator for tracks