added get- set- and addCurrentStep.
Additionally changed currentStep to be a seperate mixing step that is not part of the MixingProtocol
Made sure the method doesn't try to add an empty mixingStep
Added the extra parameter for the tested method as a constant
NOTE: a swipe that starts near the edge, goes vertical and then back to the edge is still processed
Changed the auto-generated 0 to a 1 as it is a more logical default value