AnalysisPython&Ostap
- add positive even polynomials
- add PDF for positive even polynomials
- reshuffle code for historgam parameterization, in particular
- add more extensive documentation fot all methods
- extend QMtest tests
- extend context managers from Ostap.Utils module to deal with loggers
- few minor fixes in ostap history writing
- add CPU timing to the final printout and history file
- fix two QMtest: Data & Kisa (missing input data due to cleanup of my ganga-area)