Eq rack2

This is an updated version on Nicus EQ Rack Branch.
It enables the full power of the effect back-end for the EQ Knobs as well.

You can select which EQ should work on which deck and you can load any other effect to the EQ Slots.

Next steps to merge:
* Add a second Effect slot, to utilize the Filter knob / fourth band, some Controllers offer.
* Add an effect chain to preferences for master EQ 

  
Sorry -- yea I didn't mean to suggest exposing any of that. I meant:

QList<EffectManifest> EffectsManager::getAvailableEffects(); 

would return a list of all manifests available -- the client code (DlgPrefEq) could do with the manifest list what it wishes.. check for mixing-eq flags, get the effect names, etc.