The FPS counter was called only on new frames, so it could not print
values regularly, especially when there are very few FPS (when the
device surface does not change).
To the extreme, it was never able to display 0 fps.
Add a separate thread to print framerate every second.
Limit source code to 80 chars, and declare functions return type and
modifiers on a separate line.
This allows to avoid very long lines, and all function names are
aligned.
(We do this on VLC, and I like it.)
