Fix minigun bullets sometimes failing to hit when shooting same thing twice in row
alfadur says: “the stale collision cache is searched in, so if you shoot at
same thing twice in a row, chances are it woudln't get hit”
306cedbeb213
fixed several 'retina display' images and added a bunch more (though just from upscaling the normal ones; might be nice to have 'em redrawn at a real higher resolution)