Also changes the name of the enum for now to have a prefix, since we are not using enum classes.
Furthermore this excludes true from being a preprocessed learned literal.
Solver::printStatisticsSafe() is private right now. There is no real reason for that, and as we claim that the driver is only using the regular API we should just make it public.
This PR adds a C++ unit test that explicitly calls into API functions that are not exposed by the java API. This fixes the issue of false positives in our API coverage checks, as some parts of the C++ API are legitimately not used by the java API.
It also corrects a few other minor issues.
