Similar to the library tag, this is a void pointer that should only be
used by the playlist layer.
Signed-off-by: Anna Schumaker <Anna@OcarinaProject.net>
I don't think it makes sense that callers of file_open() are expected to
check the file version after opening. This should be something handled
by the file code so we can print a consistent error message.
Implements issue #5: Better file versioning
Signed-off-by: Anna Schumaker <Anna@OcarinaProject.net>