Doubled BPM sorting

[audilin]

When "Include doubled BPM "is enabled, allow sorting by doubled BPM. I.e. instead of it looking like 85, 86, ..., 90, 170, 171, ..., 180 for the range 170-180, it could look like 85, 170, 171, 86, 172, 173, 87, 174, 175, etc.