Add offsets for held throwable objects,fix 'hovering' bottle objects

Previously, drawn throwables had an arbitrary x offset of 2 when
held. This was left over code from the old pot.lua that was
copied over. Now, each throwable child object can have its own
held position offset to fix its held position appearance. Also
reduced height of bottles on tavern map, reduced transparent
padding on the bottle image, and added offset to bottle.lua to
fix the "hovering" bottle problem. Also added offset to pot.lua
to reflect its original drawing appearance.