Can save device set as dynamic query instead of static list of devices
Merge branch 'chenxi' into working
DynamicDeviceSets are now their own class

changed my mind these types of sets are easier to implement as a
separate class.
Merge branch 'chenxi' into working
Users can save their own groups in Playback objects
Dynamic device set tweaks
Added grandmaster control to Playback

A Grandmaster controls the overall level of paramters on a lighting
console.
Updated rerender to handle scene with no light.