implement gestTestCases() for MCDC
Given a formal requirement (implemented in #3464) and an initial test
case (which can be generated either randomly or using some criteria)
this method should generate a set of test cases guaranteeing MCDC.
The concrete algorithm was given as a prototype implementation using SMT.
(from redmine: issue id 3476, created on 2018-07-16)
- relates #3477