* Added a 'FEEDS.SHA1_HASH' field to the database.
* Incremented the database version to 368.
* Added 'RDFeed::sha1Hash()' and 'RDFeed::setSha1Hash()' methods.
* Added a 'RDSha1HashData()' function.
* Optimized the podcasting subsystem so as to upload feed XML only
when the XML contents have actually changed.
Signed-off-by: Fred Gleason <fredg@paravelsystems.com>