added Dynamic Collection awareness to smart playlists, in particular the file path criteria.

It is not possible to compare the value of the file path criteria to the file's absolute path efficiently (because the absolute path is not stored in the database anymore).

So instead the value of the file path criteria is compared to the relative path, and a new criteria "Mount Point" allows to select songs on a device where the device's mount point is/contains/starts with/ends with the criteria's value.