[8016] Work at npc click table data use. Author: VladimirMangos

* New fields in `npc_spellclick_spells` for allow set npc spell click mode from quest to infinity
      or to another quest, or from reward quest.
    * Not expect (and forbid set UNIT_NPC_FLAG_SPELLCLICK in DB and set it at `npc_spellclick_spells` loading.
    * Apply some speedups for creature checks affected by spel click state

*Also add target position of 51852. By Roland

--HG--
branch : trunk

src/game/Unit.h

@@ -614,7 +614,7 @@ enum NPCFlags
     UNIT_NPC_FLAG_AUCTIONEER            = 0x00200000,       // 100%
     UNIT_NPC_FLAG_STABLEMASTER          = 0x00400000,       // 100%
     UNIT_NPC_FLAG_GUILD_BANKER          = 0x00800000,       // cause client to send 997 opcode
-    UNIT_NPC_FLAG_SPELLCLICK            = 0x01000000,       // cause client to send 1015 opcode (spell click)
+    UNIT_NPC_FLAG_SPELLCLICK            = 0x01000000,       // cause client to send 1015 opcode (spell click), dynamic, set at loading and don't must be set in DB
     UNIT_NPC_FLAG_GUARD                 = 0x10000000,       // custom flag for guards
     UNIT_NPC_FLAG_OUTDOORPVP            = 0x20000000,       // custom flag for outdoor pvp creatures
 };