WIP controller
include kerf in concentric circle calculation
Merge branch 'master' of github.com:wbw20/Tabla

Conflicts:
	Tabla.xcodeproj/project.xcworkspace/xcuserdata/will.xcuserdatad/UserInterfaceState.xcuserstate
Merge branch 'rounded_corners'

Conflicts:
	Tabla.xcodeproj/project.xcworkspace/xcuserdata/will.xcuserdatad/UserInterfaceState.xcuserstate