Core/Spells: spell effect handling improvements

* Call spell effect handlers in 4 modes:
   - SPELL_EFFECT_HANDLE_LAUNCH - called when spell is launched (cast just finished)
   - SPELL_EFFECT_HANDLE_LAUNCH_TARGET - called when spell is launched for each target in spell target map
   - SPELL_EFFECT_HANDLE_HIT - called when spell hits its destination
   - SPELL_EFFECT_HANDLE_HIT_TARGET - called when spell hits it's target from spell target map
*Correctly implement SPELL_EFFECT_TRIGGER_SPELL, SPELL_EFFECT_TRIGGER_SPELL_WITH_VALUE, SPELL_EFFECT_TRIGGER_MISSILE_SPELL_WITH_VALUE, SPELL_EFFECT_TRIGGER_MISSILE_SPELL
*Remove spell system hacks which became obsolete with this commit
Core/SpellScripts:
add OnEffectLaunch, OnEffectLaunchTarget, OnEffectHit, OnEffectHitTarget hooks for new effect handle modes and remove OnEffect hook.
A generic rule of thumb how to update your scripts (will work for nearly all cases) for spell system noobs:
if your spell script used GetHitXXXX function, you need to use OnEffectHitTarget, otherwise use
OnEffectHit

src/server/game/Spells/SpellInfo.h

@@ -228,9 +228,7 @@ public:
     uint32 GetExplicitTargetMask(bool& srcSet, bool& dstSet) const;
 
     // temporarily avalible to public
-    static bool IsPosition(uint32 targetType);
     static SpellSelectTargetTypes Type[TOTAL_SPELL_TARGETS];
-
 private:
     static bool InitStaticData();
     static void InitTypeData();
@@ -295,6 +293,7 @@ public:
     bool HasRadius() const;
     float CalcRadius(Unit* caster = NULL, Spell* = NULL) const;
 
+    uint32 GetProvidedTargetMask() const;
     uint32 GetMissingTargetMask(bool srcSet = false, bool destSet = false, uint32 mask = 0) const;
 
     SpellEffectImplicitTargetTypes GetImplicitTargetType() const;