Core/Battlegrounds: Implement power resets on arena-fight preparations (first 60 seconds before arena-fight kicks off) (Thanks to Kaelima)

Restores all player powers every 5 seconds untill arena starts (fixes possible exploit with entering arena battle with full rage or runic power)
(The 5 second timer is not 100% confirmed, as official pages only states that the power is reset after prep-time - needs feedback)
Closes issue 4805

--HG--
branch : trunk

src/server/game/Entities/Player/Player.cpp

@@ -2360,6 +2360,26 @@ void Player::RegenerateHealth()
     ModifyHealth(int32(addvalue));
 }
 
+void Player::ResetAllPowers()
+{
+    SetHealth(GetMaxHealth());
+    switch (getPowerType())
+    {
+        case POWER_MANA:
+            SetPower(POWER_MANA, GetMaxPower(POWER_MANA));
+            break;
+        case POWER_RAGE:
+            SetPower(POWER_RAGE, 0);
+            break;
+        case POWER_ENERGY:
+            SetPower(POWER_ENERGY, GetMaxPower(POWER_ENERGY));
+            break;
+        case POWER_RUNIC_POWER:
+            SetPower(POWER_RUNIC_POWER, 0);
+            break;
+    }
+}
+
 bool Player::CanInteractWithNPCs(bool alive) const
 {
     if (alive && !isAlive())