use an extra function for setfeigndeath()
like it's done with setfeared already..
allow to apply feigndeath on creatures too
avoid moving of creatures with feign death applied
and start attacking last victim when feigndeath disappears
* Added basic infrastructure for visibility update in case difference player and current view point.
Just for note: seletect additional arg way beacuse repeatable search object will slow but store pointer will not safe,
so use middle case: get view point pointer early as possible at visibility updates.
* Implement dynamic object and creature activisation while it's target of far sight spell effect
* Use this for SPELL_AURA_BIND_SIGHT, SPELL_AURA_FAR_SIGHT and SPELL_EFFECT_ADD_FARSIGHT.
* Note2: some spyglass like spells let look _around_ at long distance, this hard implement in current grid loading system
Without additional changes and not implemented (you will see empty area without creatures in likes case)
* Also fixed warning spam at CMSG_MOVE_SET_CAN_FLY_ACK receive by use proper packet sructure reading.
Also send pointer to AI constructors ans mark constructors as explicit.
This changes allow move now some generic often used AI code to CreatureAI helper functions.
