Unwanted use of --intermediate-solutions

[informarte]

When instance.solve is called with intermediate_solutions = False, minizinc is called with --intermediate-solutions.

[Dekker1]

This was a conscious decision as we found that many solvers didn't abide by the time limit give, but would not output their final solution when the CTRL-C event was passed into the solver. We currently work around this by just evaluating all solutions and storing the most recent one.

We could already change the flags for when no time limit is given, in which case there is indeed no need to evaluate all solutions. I'm, however, wary of changing this general behaviour as it caused a lot of problems in the past.