[TW] Val'kyr Shadowguard

- Old hack for valkyr stun despawn
- Move Remove UNIT_FLAG_NOT_SELECTABLE to EVENT_MOVE_TO_DROP_POS  fix
teleport to edge (maybe)
- Get 2d distance and not 3d in EffectChargeDest
- Send target z posistion to GetFirstCollisionPosition and then
MovePositionToFirstCollision since they don't work in 3d space and
flying units just stay on the same z
Core/SmartScripts: fix escort quest group-complete
Merge pull request #60 from ShinDarth/tw_fix_escort_quest_group_complete

Core/SmartScripts: fix escort quest group-complete
Merge pull request #43 from gecko32/Patch2

[TW] Val'kyr Shadowguard
[TW] Core/Spell: Rework SPELL_AURA_OBS_MOD_HEALTH

- Fixes spells where value = 1 eg.(Blood Craze, Glyph of Ghost Wolf)
when affected by auras with SPELL_AURA_MOD_HEALING_DONE_PERCENT
(Arena/Bg Dampening)
Merge pull request #61 from gecko32/patch7

[TW] Core/Spell: Rework SPELL_AURA_OBS_MOD_HEALTH
Improved 4faddb3ae49be8f5b2066ab99f55ffa4684b8e1c by adding check if player is not dead and check if player is near
Merge pull request #62 from ShinDarth/tw_fix_escort_quest_group_complete

Core/SmartAI: improved escort quest fix