Improve game filtering options

Currently, the program can only show all games that are in a particular category.

Provide an "advanced" category selector that allows categories to be:

Included: games with at least one of these may show up in the game list.
Required: games must be in all of these in order to show up in the game list.
Excluded: games in these categories will not show up in the games list.

The old category selector will remain in place, the advanced one would simply be a non-default option.

rallion / depressurizer