PlaylistFile: Cleanup PlaylistFile, fix warnings.
PlaylistFile: Cleanup PlaylistFile, fix warnings.

Cleanup PlaylistFile, fix warnings, including moving a regexp to a final
static space to be compiled prior to running.

abarisain/dmix,abarisain/dmix,joansmith/dmix,jcnoir/dmix,hurzl/dmix,hurzl/dmix,joansmith/dmix,jcnoir/dmix,0359xiaodong/dmix,0359xiaodong/dmix