Set of minor fixes and tiny improvement for LHCbMath
- Minor fix in constructor of GammaDist: initial parameter setting is incorrect. It is autocorrected as soon as parameters are changed. but incorrect stuff can appear during e.g. vizualiztaion. Now it is fixed.
- rename mediane -> median, Mediane -> Median [thanks to Marco Cattaneo]
- add quantile functions for GammaDist, LogGammaDist and Log10GammaDist
- fix some typos in comments [thanks to Marco Cattaneo]
If possible, please apply it also for 2016-patches branch