instead of throwing a rodindbexception when a unit or inferred unit pragma's content is requested but not set, return a default value (currently empty pragma).
adding cbc based refinement checks to the rodin ui, still missing work on the prolog side + some missing details
working on cbc refinement checks, reworking command send to prob
Merge branch 'feature/cbc_refinement' of github.com:bendisposto/prob into feature/cbc_refinement