Some misc changes for player purposes.

Added check for over-stacked items creating a negative amount for items over max stack count.
Added message output to player for why they are disabled when having an over-stacked item.
Added message output to player for why they are disabled when having a banned item equipped.

If users hack their stackable items using an inventory editor to a max int value, TShock will see this as a negative number and not properly disable the player. 

Also added outputs to the player if they are being disabled for a hacked item stack or banned equipment instead of them guessing why they are just frozen since the server does not send any info to the player during these occasions.