Basic health rewrite 1

First chunk of the health rewrite. This PR:
* Reworks the health system. The new system ranges from approximately -100 to 100, and updates on a 6 hour basis. Effects from food stack up a modifier on the next roll, which decreases greatly each time a roll is made, decaying to virtually nothing after the course of a day or so. As a result health is now a much better value of how healthy the player has been in the long term.
* Health now affects how fast the player heals while sleeping, with it being able to provide up to a +/- 1 in 4 chance, (the same as the default heal chance). This means low health players may not heal at all, and high health ones may heal additionally fast. Also performed a slight rework on the healing system while asleep, which now can handle stacking chances for players to heal much better.
* Made AEP_SICK artifacts have an effect again.
* Many things that used to affect health directly now affect your health modifier instead.
* Fixed a few small coding logic errors I stumbled upon.
* Styled Player::mend()
This is fixed, as you can see on the file changes tab, but the main page won't show it because it ended up on the other side of the "old" parenthesis.