Many improvements to Sequence impleentation
Many improvements to Sequence impleentation

it's reusable now - call 'executeAgain' in case of error, or even in completion block.

maximkhatskevich/MKHSequenceCtrl,maximkhatskevich/MKHSequenceCtrl,maximkhatskevich/MKHSequence,maximkhatskevich/MKHSequence