[8381] Some refactoring work in Unit::m_currentSpells code. Author: VladimirMangos

* Restrict access, use enum args, move some repeated code parts to function.
    * Make m_selfContainer set only part of Unit::SetCurrentCastedSpell

--HG--
branch : trunk

src/game/Spell.h

@@ -243,6 +243,7 @@ enum SpellTargets
 class Spell
 {
     friend struct Trinity::SpellNotifierCreatureAndPlayer;
+    friend void Unit::SetCurrentCastedSpell( Spell * pSpell );
     public:
 
         void EffectNULL(uint32 );