Coalesce the title and file name to get consistent ordering

This should make tracker order (by title, or by file name if no title) match the UI order (by "title", which uses the file name if there is not title)

The only mismatch I've found is one file that has a space at the start of the title. Tracker seems to include the space (and so includes it in the first batch of files, because 0x20 comes before the alphabet at 0x41) but then the UI ignores it (and so a title beginning with "S" comes after all of the E-R titles that it hasn't loaded yet)

Fixes #6 (closed)