Move vinyl control processing to the engine thread

Get rid of the separate vinyl control processing threads.  Move various operations around to keep the engine thread operations as lightweight as possible. 


On 09/16/2014 09:07 AM, Owen Williams wrote:
> The vinyl processing code is very tolerant of errors. Dropping samples
> is fine, and won't cause any problems on the processing side.

Since I intend to eventually use the vinyl control subsystem to handle 
moving platter controller scratching, I fear that assuming it being okay 
to drop samples will not be okay when it comes to controller messages, 
as it would result in sticker drift.

Or is this not relevant since you're talking about samples (before 
parsing into digital values?) The controller subsystem would be passing 
already-parsed digital values, none of which can afford to be lost.

Sincerely,
Sean M. Pappalardo
"D.J. Pegasus"
Mixxx Developer - Controller Specialist