Blocked spelleffect (area or field) on ridden chars and other fixes

[DavideRei]

Blocked spelleffect on ridden chars if the spell has field or area flags. Fixed duration of hallucination spell. Fixed wrong layer for potion delay. Fixed wrong sound id for changing monster sounds schema. Fixed Attacker_GetHighestThreat: return -1 would make the NPC threat lesser than the ATTACKER_THREAT_TOLDBYMASTER and make CChar::NPC_GetAttackMotivation not work correctly for attacking pets. Fixed NPC_Act_Follow use combat target even if the npc is not in combat. Maybe related to #1215