Core/Random: Changed random functions returning doubles to return floats

* They were all cast to float at use anyway
* Improves roll_chance_f performance (rand32() is now called internally by uniform_real_distribution once instead of twice)

src/server/game/Spells/SpellEffects.cpp

@@ -4914,7 +4914,7 @@ void Spell::EffectTransmitted(SpellEffIndex effIndex)
         //GO is always friendly to it's creator, get range for friends
         float min_dis = m_spellInfo->GetMinRange(true);
         float max_dis = m_spellInfo->GetMaxRange(true);
-        float dis = (float)rand_norm() * (max_dis - min_dis) + min_dis;
+        float dis = rand_norm() * (max_dis - min_dis) + min_dis;
 
         unitCaster->GetClosePoint(fx, fy, fz, DEFAULT_PLAYER_BOUNDING_RADIUS, dis);
         fo = unitCaster->GetOrientation();