* sequences to ti transformations, support for seq_lengths input, update reference implemetations, add new tests
* fix python api, update sequences to ti transformation
* fix sequences to ti transformation
* Update sequences to TI transformation: fix reverse sequence support
* update single layer tests, fix TI reference impl, fix Sequences to TI transformations
* ngraph code style
* fix build
* fix ngraph python api
* resolver review comments, refactoring
* Resolve review remarks
* delete xfail
Alexey Suhov