First step to multi-threading save: stop using global buffer for rendering
Multi-thread the save.  One thread per model.
Fix another usage of a global variable
Merge branch 'master' into threaded

Conflicts:
	xLights/TabSequence.cpp
UPdate the threads to have the previous thread let it know how far to go instead of polling the previous thread since the previous thread could be done and deleted.
Add "Fast Save" option
Change from wxColor to our own class to avoid OS level calls that are not needed.
Fix a few things that are causing issues on the Mac on a background thread
More updates to get the threaded rendering correct by avoiding a global "play" variable.
Avoid a bunch of HSV -> RGB's conversions that really only need to happen once.
Merge remote-tracking branch 'origin/master' into threaded
Try to fix issue on windows by removing unneeded controls
Added initial support for model groups.
Merge branch 'threaded' of https://github.com/smeighan/xLights into threaded
Fixed close button on PreviewModels.cpp.
Clear models in group listbox when new group is created.
Remove some code that isn't used and was causing buffer overwrite issues.
Add some extra checking to make sure the starSizes add up to less than the number of nodes.