Updated for carrying feature of 0.3x RC2

Added a new predefined item size: ITEM_SIZE_CARRY, picking up an item
with this size will activate the new player special action:
SPECIAL_ACTION_CARRY, this is also combined with new pickup/drop
animations.

Item has a new callback:
OnItemRemovedFromPlayer - Called when an item is removed from a players
hands by the script (not by him dropping or giving it)

Container has a 2 new callbacks:
OnPlayerAddedToContainer - Called after an item has been added to a
container, and after the container item index has been updated.
OnPlayerTakenFromContainer - Called after an item has been removed from
a container, and after the container item index has been updated