Scripts/HoO: Templeguardian Anhuur Changes

*Temple Guardian Anhuurs Devine Reckoning will now target a random target instead of his victim
*Also his heroic version of Devine Reckoning will now heal Anhuur
*Reverberating Hymn will now get interrupted when Anhuur takes any damage when the shield of light is gone
*simplyfied the shield counter and damage check
*Implement the achievement 'I hate that Song'.

*possible todo: spell attribe usable_while_stunned may be required also for channeled spells to make the reverberating hymn work properly
because the events are getting resetted on shield cast because else this would cause a event stacking after a too long shield phase which is pretty ugly