Fix issue #88 by changing the behavior of setProperties().

For file types that support multiple tag standards (for example, FLAC
files can have ID3v1, ID3v2, and Vorbis comments) setProperties is now
called for all existing tags instead of only for the most recommended
one.
This fixes the problem that under some circumstances it was not possible
to delete a value using setProperties() because upon save() the call to
Tag::duplicate recovered that value from the ID3v1 tag.