Core/Unit: rewrite of the attack table system

- Removed a bunch of duplicated code
- Fix off-by-one errors in Unit::RollMeleeOutcomeAgainst and Unit::MeleeSpellHitResult (TC's combat table was actually of 100.01%)
- Implemented boss-level hit table (6.5% dodge/14% parry), bosses only had 5.6% of each until now
- Updated formula for chance and damage of Glancing hits

Sources:
- http://wow.gamepedia.com/index.php?title=Attack_table&oldid=2071465
- http://web.archive.org/web/20100903145646/http://www.mmo-champion.com/threads/650071-Expertise-Hit-for-Paladins-%28updated-for-3.3%29?daysprune=60

src/server/game/Entities/Unit/StatSystem.cpp

@@ -666,7 +666,7 @@ const float m_diminishing_k[MAX_CLASSES] =
     0.9720f   // Druid
 };
 
-float Player::GetMissPercentageFromDefence() const
+float Player::GetMissPercentageFromDefense() const
 {
     float const miss_cap[MAX_CLASSES] =
     {