Symmetry breaking code refactoring about fortress HOT 2 OPEN

A few comments (partially following up on my Slack discussion with Nancy):

1. I believe that SymmetryBreakingTransformerSI is intended to be used on problems where sort inference has not already been performed, and you explicitly do not want to keep the inferred sorts once symmetry breaking is done. SymmetryBreakingTransformerSI leaves the sorts unchanged when it is finished - the sort inference is temporary. We introduced this for evaluation purposes, but it is not clear that you would want this behaviour for standard uses.

2. HyperGraph and Microstructure were used during my undergrad thesis, but have no practical use in Fortress (they were a theoretical tool mainly), so can be removed if you wish.

from fortress.

Additional info from Joe: Even through the FortressTWOCompiler_SI() does not seem to use the SymmetryBreakingTransformerSI, the compilation steps include the SortInferenceTransformer so it does do sort inference. "The reason does not take this approach, is that we wanted to use sort inference for the purposes of symmetry breaking only, but not actually change the sorts of the problem, so that we have as close to an apples-to-apples comparison as possible (maybe changing the sort names changes how Z3 behaves, for example). So the sort inference in v3 is used temporarily during the symmetry breaking process, then thrown away later "

from fortress.