gui cleanup -- partial fix for #34

--fixed alpha blending for hint items.
--remove extra GLattribute stack push/pull from item-stack rendering --
should help with fps anytime item-stacks are rendered
--enable push/pop attrib on tooltip rendering (once per frame is not so
bad) -- fixes lighting w/tooltips displayed
****need to find proper solution for above fix...could probably examine
the GL state-stack to see what gets flipped
...