[Open-graphics] Video interrupt enable/disable

[Timothy Normand Miller]

One example of a case where we want to do a one-shot vsync interrupt
is when we want to update the color table.  Depending on how the color
table is implemented, writing to it during active video may glitch
pixels, so we wait for blank and update then.

-- 
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Open Graphics Project