Removed ezSAT built-in brute-froce solver
Removed ezSAT::assumed() API
ezSAT bugfix: don't call virtual methods in base class constructor
Added ezSAT::eliminated API to help the SAT solver remember eliminated variables
ezSAT: Fixed handling of eliminated Literals, added auto-freeze for expressions
ezSAT: Added frozen_literal() API
fixed freduce for Minisat::SimpSolver: use frozen_literal()