Update min-clamped plot with multi-trial results
Add box-plots comparison of VPR and cyplace

Add IPython notebook discuss the post-routing results of placing all 20 MCNC
netlist benchmarks using:

 1. VPR's place bounding-box annealer,
    running in _fast_ mode _(i.e., `inner_num=1`)_
 2.  VPR's bounding-box place annealer,
    running in default _fast_ mode _(i.e., `inner_num=10`)_
 3. `cyplace` annealer using _Star+_

For each annealer, we conducted 10 trials, _i.e._, we placed each netlist 10
times with 10 unique random-number-generator seeds.
Add compare_routed program, add docs to routing...

Add `compare_routed` program.
Usage:

    compare_routed.py [-h] results_dir label [label ...]

    Run VPR place based on net-file namebase

    positional arguments:
      results_dir
      label

    optional arguments:
      -h, --help   show this help message and exit

Add doc-strings to routing-results pandas processing methods.
Add notebook plotting significance of critical-...

Add IPython notebook plotting the routing critical-path-delay results from
running 10 trials for each of the following place algorithms:

 * `vpr-not_fast-bounding_box`
 * `vpr-fast-bounding_box`
 * `cyplace-7a8d71d4`

Note the _$p$-value_ significance markings on the plots.  The significance
_$p$-values_ are computed using a [Wilcoxon signed-rank test][1] and are
labelled on the plot above either a _red_ or _green_ arrow, pointing to the
relevant means in the box plot.

A _green_ arrow indicates that the $p$-value is less than 0.05, such that the
null-hypothesis may be rejected, indicating that the means are not
statistically likely to be due to drawing from the same population.  If the
$p$-value is greater than 0.05, the arrow is _red_.

[1]: http://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test
Add n-way paired p-value arrows to routing plot...

Add n-way $p$-value indicator arrows to routing plots.  Previously, the arrows
were only between adjacent pairs in the box plots.

Add discussion of results to `Routing - significance comparison box-plot`
IPython notebook, including comparison of VPR _fast_ vs. `cyplace`.