AttrBold should be applied after AttrReverse.
AttrBold should be applied after AttrReverse.

It fixes unexpected behaviour in situations like this:
  termbox.Cell{
    Fg: termbox.AttrReverse | termbox.AttrBold,
    Bg: termbox.AttrReverse
  }

With previous logic AttrBold goes to Bg instead of Fg as user expected. Now it's
correct.

VladimirMarkelov/termbox-go,nsf/termbox-go,wallyqs/termbox-go,lcaballero/termbox-go,supriyantomaftuh/termbox-go,mboersma/termbox-go,michaeldv/termbox-go,swdunlop/rawtty-go,supriyantomaftuh/termbox-go,michaeldv/termbox-go,VladimirMarkelov/termbox-go,wkjagt/termbox-go,swdunlop/rawtty-go,justintung/termbox-go,limetext/termbox-go,mboersma/termbox-go,gdamore/termbox-go,lcaballero/termbox-go,tcolar/termbox-go,justintung/termbox-go,gdamore/termbox-go,wkjagt/termbox-go,pwiecz/termbox-go,pwiecz/termbox-go,wallyqs/termbox-go,tcolar/termbox-go,limetext/termbox-go,nsf/termbox-go