Indexed database for searching

[dopefishh]

Offer an option to define a database structure that is suitable for your database. Currently the database is sorted on file structure but a shadow database could be maintained that is sorted on user specified tags. e.g. artist - year - album

Tags should be an option and also alphabetical, e.g. the first letter of the artist tag.

For now the following things need to be done to close this:

• [x] Convert the linked list db to a sorted array db
• [x] Free the db's
• [ ] Fix memory leak in freeing
• [ ] Serialize the shadow db
• [ ] Search in the shadow db instead of the normal db

Future improvements:

• [ ] Incremental updates instead of a full rescan

[dopefishh]

The format specification can be used for this