Moving comment to where it makes sense
Functions that operate on data in CNF should be in CNF
Don't display the internal variable numbers during debug

When simplifier is extending the solution, everything is in external
mode, so don't "help" the developer by mapping everything back to
internal. That was only needed before the new system.
Remove redundant comment

It's obvious we check the stats to make sure things are OK especially
before extending the solution
Don't expose interToOuterMain and its reverse

Instead, use accessor functions to map variables, literals, and vectors
of literals. This also allows us to see how these important data pieces
are being used