feature/variants/wounds_and_vigor

Adds support for the Wounds and Vigor variant from Ultimate Combat. I also cleaned up the health computation a bit and made the tooltip popups a little less aggressive on the Attributes tab.

I believe this also fixed an error with maximum hp awards on first level applying to each source of hitdie when multiclassing, though it doesn't appear to respond well to resorting the class lists. Also fixed an issue wherein players were underawarded autocomputed health. There's no 0 on a hitdie, so the correct formula for health income is:

1 + (hit_die-1) * auto_rate;