#13 Monitor Media Library folders for file changes

[Anders Sandvig]

Add option to monitor folders in Media Library for
changes and automatically update the library.

1) Whenever a file is modified in a Media Library folder,
rescan it to update filename, extended info and
metadata.

2) Whenever a file is deleted from a Media Library folder,
remove it from the library list.

3) Whenever a new file appears in the Media Library
folder, scan it and add it to the library list.

Note:
If a file is renamed it should probably be removed (the
old file was deleted) and re-added as a new file. It
would be cool if we could avioud this though (i.e. check
new file's checksum, size and metadata against cached
values to detect that the new file is infact an old file
just renamed, and update the entry in the library
(keeping the index and not breaking any ongoing search)

[Anders Sandvig]

Look into implementing this using SHChangeNotifyRegister().