[8422] Implement far sight like spells work for long distance.

[8422] Implement far sight like spells work for long distance.

* 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.