Absorb calculations are handled out of order

[Wes Chao]

As implemented, the order appears to be left to right, applying main attribute and sub attribute for each monster.

The correct order is main attribute left to right, followed by sub attribute left to right.

Assigning priority critical since this causes calculations to return an incorrect result.

[Wes Chao]

Fixed, along with a warning if the enemy's health is not specified (since this is needed for accurate absorb calculations).

Unfortunately, the warning implementation causes a bug in Safari where empty health and absorb at the same time causes the form to get submitted and the page to reload, thanks to Safari not implementing full support for HTML5 form validation.