mouseover attribution improvements

utfgrids and vector mouseovers playing more nicely together now…moving
cursor from one feature to another now displays appropriate popups.
(remaining issue is moving cursor from a position that is positioned
over more than 2 mouseover layers to one that contains the 3rd
mouseover layer (or 4th or 5th, etc)…working on this next)
mouseover attribute improvements part 2
mouseover attribute improvements part 3

(no more lingering popups)