Added an update funtion to all UI elements.  This will be called every frame prior to drawUI.  It takes a pointer back to the HumanGameView so it can access HumanGameView data, like window transformation functions and the like.
Forgot to add update to UIPortData in last commit, added now.
Added an updateUI() function to HumanGameView that calls update on all the UI elements.
Minor spacing change.
Had to go back and change UIElement's update function to take a non-const argument, since we have to get at non-const things through it.
Added some update code for UIPortData.  Now they all update their own position, gold and rum amounts.  To do this mapToWindow() and windowToMap() in HumanGameView had to be made public.
Added an accessor to map_tile_size because the UI port data needs to know this to know how to size its own text.