Add code which ensures player gets certain items / weapons early in megawad

When ObHack generates a megawad, one annoying issue is that certain items which the player should have early in the game, such as the backpack or super shotgun, sometimes do not appear until fairly late in the megawad. For example, in the old ObHack-696 branch, the backpack did not arrive until MAP08 with its default 2FreeDoom1 seed, an issue I fixed by forcing MAP01 to always have a backpack and super shotgun.

The correct way to fix this is to have a list of items we always add first before adding any other items or weapons to maps. We also need to make sure that, no matter how small they want the map and how many key/switch puzzles they want in the map, to always have at least one weapon/item quest in every map.

samboy / ObHack

Add code which ensures player gets certain items / weapons early in megawad #6