Health ruleset update v7

[CodeWringer]

• [x] Injuries when healed can now leave behind a scar, which is a new type of embeddable document.
  • A scar has properties such as: name, limit, description and effects (modifiers).
• [x] Introduce types for character states. See the "States" section below "Character".
  • [x] These states must be trackable on the "Health" tab of a character.
  • [x] These states must be user-definable.
• [x] Maximum magic stamina -> Sum of arcana + all known magic school skills, divided by two and rounded up.
• [x] Add "scar" documents.

[CodeWringer]

Modifers is pushed into its own separate issue #212