Control Exp boost from Arka Buff

Allow us to control Exp boost from Arka Buff. Some servers are high exp and 20% is too little, others are low exp and 20% maybe very significative.

BuffEffectMananger.xml

<Period>
		<Buff Index="179" EffectType1="0" EffectValue1="25" EffectType2="0" EffectValue2="0" Duration="604800" Name="Fire Tower" />
		<Buff Index="180" EffectType1="0" EffectValue1="50" EffectType2="0" EffectValue2="0" Duration="604800" Name="Water Tower" />
		<Buff Index="181" EffectType1="55" EffectValue1="5" EffectType2="0" EffectValue2="0" Duration="604800" Name="Earth Tower" />
		<Buff Index="182" EffectType1="85" EffectValue1="30" EffectType2="0" EffectValue2="0" Duration="604800" Name="Wind Tower" />
		<Buff Index="183" EffectType1="86" EffectValue1="10" EffectType2="0" EffectValue2="0" Duration="604800" Name="Darkness Tower" />
		<Buff Index="184" EffectType1="20" EffectValue1="0" EffectType2="0" EffectValue2="0" Duration="60" Name="Resurrection Penalty" />
		<Buff Index="246" EffectType1="101" EffectValue1="200" EffectType2="102" EffectValue2="50" Duration="1800" Name="Archangel's Absolute Weapon Skill" />
		<Buff Index="247" EffectType1="0" EffectValue1="0" EffectType2="0" EffectValue2="5" Duration="0" Name="Ferea Party EXP Buff" />
</Period>

Add the possibility to modify exp value (20%) to a desire value. Thanks.