Resolves #8. Looks like many changes, but it's always the same. Main points:
Consistently used log4j2 for logging in all classes with output, removing all previous Log usages and System.*.println calls.
Handled the solvers' logs so they don't log per default. To activate logging, a user can set the SolveParam.DISPLAY_OUTPUT to true or set the logging level to at least DEBUG.
This results in very clean logs by default, with an easy flag to follow the progress of larger MIPs.
Resolves #8. Looks like many changes, but it's always the same. Main points: