add description for dominion power.

Powers are a type of ability that increase (or decrease) a unit's stats depending on the conditions of the province the unit is situated in. They can be binary (either on or off) or scale incrementally with more extreme conditions (e.g. temperature scales). Some powers can be activated by battlefield enchantments (e.g. storm power via Storm, dark power via Darkness). The stats affected are attack skill, defense skill, strength and combat speed, with a few exceptions.

Powers include (x is the value of the power):

• Chaos Power: gain x stats per point of turmoil, lose x stats per point of order. Every 15 points of unrest count as 1 point of turmoil, but there can be no more than +3 points of turmoil total.
  Examples: Lankan demons, Yomi-line demons.
• Cold Power: gain x stats per point of cold, lose x stats per point of heat.
  Examples: Niefel Giant, Thrymsgode, Rimvaetti.
• Dark Power: gain x stats when in the dark.
  Examples: Fiend of Darkness, Mandeha.
• Death Power: gain x stats per point of death, lose x stats per point of growth.
• Dominion Power:
• Fire Power: gain x stats per point of heat, lose x stats per point of cold.
  Examples: Fire Elemental, Burning One, Marid.
• Magic Power: gain x stats per point of magic, lose x stats per point of drain. Also affects MR. Additionally affects stealth, up to a maximum of +5 stealth in magic 3.
  Examples: Lemur Consul, horrors.
• Sloth Power: gain x stats per point of sloth, lose x stats per point of productivity.
• Storm Power: gain x stats during a storm. All vanilla units with Storm Power also have Storm Immunity.
  Examples: Air Elemental, Storm Demon.

Some powers are dependent on the season instead of local province conditions. These are:

• Seasonal Powers: affect a unit's hit points. During the peak of the appropriate season, the unit gains an x% bonus to maximum hitpoints. After this season, maximum hitpoints reduces until the peak of the opposite season when they suffer an x% penalty, after which they begin rising again as the appropriate season approaches.
  Examples: Red Guard, Summer Lion, Fall Bear, Winter Wolf.
• Power of the Turning Year: gain x to strength, attack skill and defense skill at the height of each season.
  Examples: Duiu of Thunder

Unit Abilities