Remove pointless vertical alignment logic

The only time it has an effect is when font substitution occurs, and the
end result tends to be worse than doing nothing at all.
Draw the active line box on top of the grid columns
Fix ugly extra grid line drawn when the first row is selected
Push more of the painting logic into the grid column classes
Change the background color of the CPS column when the value is excessively high
Don't show a CPS value for lines under 100 ms long
Make the CPS warning thresholds and color customizable
Update ffms2