Adds the Mage Knight metaclass, and its six sub-classes.

Forum discussion thread: http://forums.te4.org/viewtopic.php?f=50&t=48329

Phoenix Knight: Powerful warriors who blast their foes with solar fire while calling healing light upon their allies. Their solar fire attacks will strike as either fire or light damage, whichever will hit their target the hardest, and their potent healing and cleansing abilities make them tough opponents to bring down.

Mind Knight: Psionic warriors who strengthen their mental abilities by tapping into their inner magic. Adept at telekinesis, telepathy, and teleportation, they are mobile scouts who can quickly get a lay of the land and sow chaos among their foes with physical and mental debilitations, or even outright compulsions.

Storm Knight: Swift skirmishers who rely on extreme mobility and powerful lightning magic to strike their foes down and avoid reprisals. Extremely fast and difficult to pin down, they can cast entire enemy units into disarray with their wealth of area attacks. All mage knights can cast while they fight, but experienced storm knights are also able to fight while they move.

Earth Knight: The heaviest of infantry, earth knights hammer their foes with physical and natural forces while shielding themselves with the power of the earth. Highly resilient in the face of any attack, earth knights provide a slow and steady offense supported by powerful gemstone shields and the endurance of a living mountain.

Sea Knight: Healers first, fighters second, battle mages a somewhat distant third, while sea knights lack the raw offensive power of other mage knights, they make up for it with amazing personal defense and recovery abilities. And though their attacks may be individually weak, like the sea itself, they are able to wear down even the strongest defenses eventually, eroding their opponents away with gradually strengthening spells, making them terrors in a battle of attrition.

Mana Knight: Experimenting pioneers who do amazing things with raw magical energy. They have the most conventional magical training of the mage knights, even if they sometimes put it to unconventional use. Their arcane attacks can overwhelm the powers of other spellcasters, and while they lack the scope of power of full-fledged archmages, they are masters of the fundamentals of the various arcane schools.