[mythtv] ReplayGain support for MythMusic

[Chris Hamilton]

>> We are focusing on getting 0.21 out the door right now,  so feature patches 
>> are taking a back seat. With luck 0.21 will be released in a week or two 
>> (circumstances allowing, so please give us leeway).
> 
> Aha.  I didn't realize 0.21 was that close.  No problem.

With 0.21 out the door, any chance of getting my preamp patch rolled in?
 This will let me start working on the rest of the ReplayGain stuff.

http://svn.mythtv.org/trac/ticket/4804

Cheers,

Chris