Adjust EffectPlayerPull so that it accounts for Z difference

Fixes pull issues in murmurs room

The initial formula was the following:
distance/horizontal speed = time
1/2*gravitational acceleration*time = initial vertical speed

Problem is when intial Z != final Z
Then the formula is as following:
(final Z - initial Z + 1/2*gravitational acceleration*time*time) / time = initial vertical speed
if you set final z - initial z both to 0, or the same number, you get the initial formula

WOTLK:
The wotlk core uses movespline to compute this. MoveJump is used all over scripts with guessed Max Height, which sounds quite bad, since that should be a computed
value stemming from spells. (client is sent horizontal and vertical speed in packet)
In future need to change from max height to vertical speed so that it reflects client usage.

src/game/Spells/SpellEffects.cpp

@@ -54,6 +54,7 @@
 #include "Entities/Vehicle.h"
 #include "G3D/Vector3.h"
 #include "Loot/LootMgr.h"
+#include "Movement/MoveSpline.h"
 
 pEffect SpellEffects[TOTAL_SPELL_EFFECTS] =
 {
@@ -11592,16 +11593,15 @@ void Spell::EffectPlayerPull(SpellEffectIndex eff_idx)
 
     float x, y, z;
     m_caster->GetPosition(x, y, z);
-
-    // move back a bit
-    x = x - (0.6 * cos(m_caster->GetOrientation() + M_PI_F));
-    y = y - (0.6 * sin(m_caster->GetOrientation() + M_PI_F));
-
-    // Try to normalize Z coord because GetContactPoint do nothing with Z axis
-    unitTarget->UpdateAllowedPositionZ(x, y, z);
-
-    float speed = m_spellInfo->speed ? m_spellInfo->speed : 27.0f;
-    unitTarget->GetMotionMaster()->MoveJump(x, y, z, speed, 2.5f);
+    float dist = unitTarget->GetDistance2d(m_caster);
+
+    // Projectile motion
+    float speedXY = float(m_spellInfo->EffectMiscValue[eff_idx]) * 0.1f;
+    float time = dist / speedXY;
+    float speedZ = ((m_caster->GetPositionZ() - unitTarget->GetPositionZ()) + 0.5f*time*time*Movement::gravity) / time;
+    float moveTimeHalf = speedZ / Movement::gravity;
+    float max_height = -Movement::computeFallElevation(moveTimeHalf, false, -speedZ);
+    unitTarget->GetMotionMaster()->MoveJump(x, y, z, speedXY, max_height, 2.5f);
 }
 
 void Spell::EffectDispelMechanic(SpellEffectIndex eff_idx)