TagDialog Metadata Should Update Only If Changed

[Alejandro Wainzinger]

So after implementing EditCapability for IpodMeta, I noticed that even
though I didn't implement editing titles to update on the Ipod's
database, it was getting done anyway.  I realized that setArtist() was
being called even though the artist tag wasn't changed at all.  Is
there a reason that TagDialog blindly updates artist even though it's
unchanged, am I missing something, or....?