sym_load_problem()

Reads the problem data and sets up the root subproblem. This includes specifying which cuts and variables are in the core (those that are initially present in every subproblem during the search process) and the additional cuts and variables to be initially active in the root subproblem. By default, SYMPHONY reads an MPS or GMPL file specified by the user, but the user can override this default by implementing a user callback that reads the data from a file in a customized format (see Section 3.4).