This is a pretty big one! Someone I know suggested that I should
make the textboxes able to stay on the screen for longer, so I've
added an option for that! In the process I also changed Fire and
Altfire to advance to the next box immediately (rather than skipping
outright), so that if you select a slower speed you can still make
the text go to the next one after you're finished reading one.
The fix is simpl to make blitTextInPlace center text to the
screen rather than the text creation doing it. That way you don't
get weird behavior with screen_blitText (which already handles centering).