The magic-strength of a hero now checks if the hero has a spellbook and at least one combat-spell.
The impact of knowledge and spellpower to the hero's magic-strength is now also depending on it's current and max mana-pool-size as an empty mana-pool does not exactly contribute well to fights.
Replaced every call of getFightingStrength() with getHeroStrength() which uses both the fightingStrength and the (reworked) magicStrength to guess how much stronger a hero-lead army is.