Add System Set Filters

[Zeenobit]

This is a PR to address Issue #26

I've added a new include_system_set member to Settings. Inside included_systems_sets, I'm checking this mapper to skip any unwanted system sets.

I think the logic inside included_systems_sets could use a bit of clean up, but it seems to be working correctly based on my testing.

I've included print_schedule_graph_advanced_filters.rs as an example/test.