src/oping.c: Change the order of graphs.
src/oping.c: Improve comments.

Also remove dead code.
src/oping.c: Fix pretty ping graph movement.

Fixed the wrap-around case and adds support for windows larger than the
history size.
src/oping.c: Fix status output.

This is a really dirty hack: If the percentile and/or median output
decreases, the output may have less characters than previously. Add
spaces at the end of the string to clear digits with may have been
there, to avoid the "maximum" value be appear to go through the roof.