Revert "Update ai_gather.lua"

This reverts commit 5fb34925c330d1c67bfdcbcdddd019e61373383e.
Revert "Revert "Update ai_gather.lua""

This reverts commit b3290648950fa4491a97430478f7bca702600b34.
Patch Bug Unlootable

Bug: Bot will try to look a blacklisted lootable nonstop.
Reason: loot cause checks for the presence of lootable that is not
blacklisted while loot effect checks for the presence of all lootables
including blacklisted ones and will therefore try to loot it.
Fix: Filter out blacklisted lootables in loot effect function.
Merge pull request #21 from Haxicon/Patch-Loot-Bug

Patch Unlootable Bug