Parry Scaling

Revert parry deflection values to % of weapon damage, with heavy Nerf (upper limit reduced to 50% of offhand weapon damage). Updated Dual Weapon Defense to match.

I believe this achieves the kind of performance Shibari was going for. This scales well throughout the game from 1-2 points of parry deflection at game start to ~ 25-35 points of parry deflection at end game. (The last merged formula returned nearly constant parry values from talent level 1 to talent level 30+ due to compounded diminishing returns.)

Basing parry value on % of weapon is superior to a more explicit formula because:

Safe scaling is built into the formula, and will scale safely to all levels and difficulties. Parry values will not become either trivial and overpowering, provided weapon damage between attacker and defender remains consistent (i.e. until ToME breaks).

Balancing the deflection value is much simpler: Only the values in the combatLimit call in getDeflectPercent need to be adjusted. Balancing for any other changes in weapons, weapon types, armor values, weapon damage scaling etc. in the future is automatically incorporated, so we won't have to come back and tweak this again.

It gives the player another way to customize his character: You can trade offense (best weapon in mainhand, full damage) for defense (best weapon in offhand, reduced damage with better deflection values.)