oping, noping: Implement percentile reporting.
Initial implementation of a box plot.

Still needs a command line switch and documentation.
noping: Add the "-g" option.
src/oping.c: Add a "-g histrogram" option.
oping manual page: Document the "-g histogram" option.
noping: Color response times based on their percentile.

Update the histogram's "ratio" array after ever response and use that to
color the response time in the noping application.
src/oping.c: Make sure the reported percentile value doesn't exceed the maximum.
src/oping.c: Define thresholds for coloring green and yellow in a central place.
src/oping.c: Exit early if no host could be resolved.

Otherwise "noping" would drop the user into an empty ncurses window,
which is very confusing, annoying and unexpected.
src/oping.c: Add median and 'n'th percentile, remove average and stddev.

Average and standard deviation are not very useful for network latency.
Median and (95th) percentiles are routinely used to measure network
performance, so provide them instead.
src/oping.c: Rewrite of the percentile code.

Rather than bucketizing RTTs and approximating the percentile, keep the
last 900 replies (15 minutes by default) in memory and calculate the
percentile from that.

This allows the "prettyping" graph to "move to the left", which is a much
nicer user experience IMHO.
src/oping.c: Switch graphs when pressing "g".
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.
Bump version to 1.8.0; Update ChangeLog.