Path condition real solutions

[domainexpert]

This adds an option -compute-real-solution to get real number solutions for the input values in test<N>.reals files from the path condition constraints. It seems for at least the simple test examples, the solution obtained equals the integral solution. It cannot be ascertained if this will always be the case.

[Himeshi]

@domainexpert Were the simple examples, the ones that exist in the fp-examples repo?