Core/AH: Fix memory leak

Fix memory leak in Auction House when creating an auction with stackable items and a stack of the same amount in the inventory. Leak added in 15a2acfb528728b824291cb49cdd9196e6f0d57d .
Core/Misc: Fix warning

Partially revert f0a742a8c471ba948d5d86c1ab5e3a74329a9a92 to fix a warning about unhandled switch case (the same case that Coverity reported as dead code) .
Core/Player: Fix logic for questgiver cast spell
DB/SAI: Fix some duplicate aura errors and clean up the SAI.
Core/SAI: Make SMART_ACTION_SET_INGAME_PHASE_MASK set the phasemask of the target_type instead of always the source calling the action type.
Core/SAI: Using SMART_ACTION_SET_FOLLOW with target_type 0 (SMART_TARGET_NONE) will now stop the following completely. Fixes 6 scripts in a clean TDB already using this functionality even though it wasn't implemented.
DB/SAI: Fix two wrong action_types that would make the creature cast the Death Touch spell on no target (SMART_TARGET_NONE) instead of move to given target_x/y/z/o co-ordinates.

The person who wrote this script accidently used action_type 11 (SMART_ACTION_CAST) instead of 69 (SMART_ACTION_MOVE_TO_POS), and since the action_param1 field of SMART_ACTION_MOVE_TO_POS is the motion id (point id given back to SMART_EVENT_MOVEMENTINFORM), it was set to 5. Ironically, the first parameter of SMART_ACTION_CAST is the spell id and it was spell id 5 is Death Touch.
However this script would do nothing because I changed it so that SMART_TARGET_NONE no longer functioned as SMART_TARGET_ACTION_INVOKER in this commit: 9653576cb4cc9449898d6af691c045d68e9361c5. Before this commit, though, it WOULD cast Death Touch. Fun fun fun.
Core/SAI: In all npc flag related action_types we now check if the target is a creature instead of an unit (creature/player).
Core/SAI: Using the action_type SMART_ACTION_SET_REACT_STATE now sets the react state of the target_type. Won't break any scripts as all current cases of this action_type have target_type 1 (SMART_TARGET_SELF).
Core/SAI: Fix compile
Core/SAI: Don't limit SMART_ACTION_SET_INGAME_PHASE_MASK to unit targets only. Thanks to @Shauren for the notice.