Unique appearances

I haven't been happy with how every tribe member looks the same, because the long term goal is to make each of them a unique person.

As the first step towards this goal, I've added variations in hair and beard styles and colors. This took a while not just because drawing sprites is a time intensive process, but also because I took the effort to write an appearance generator system that doesn't repeat itself as long as there's still unused combos of appearance modifiers.

For now hair and beard have three different styles each with three different colors, plus a bald/beardless variant. There's a bit of a repetition issue with the last one because I have three different "hair colors" for the bald and beardless combo, but I reckon this is a minor issues and I've got bigger fish to fry right now.