This reverts commit 8a6a0b7a.

Fixes #1.

There is only one page.

Calculate JL divergence for historical sky maps

See merge request !2

Calculate the Jenson-Shannon divergence between baseline and new
sky maps for historical events.

The Jenson-Shannon divergence is the symmetrized Kullback-Leibler
(KL) divergence computed using base 2 logarithms and divided by 2.
It is symmetric and has a value between 0 (for identical
distributions) and 1.

In this patch, we compute the divergence, but it is not yet added
to the MkDocs output.

Use same projection for baseline and new volume plots

See merge request !3

The script ligo-skymap-plot-volume automatically chooses a
projection that is aligned with the principal axes of the 3D pdf.
This projection is a cosmetic choice. Small differences in the
projection can result in large image differencdes. Align both the
baseline and the new volumetric plot to the baseline pdf.

Suppress contours in 2D images

Closes #3

See merge request !1

The cosmetic positioning of the contour labels causes spurious
differences in the image comparisons.

Fixes #3.

Fixes #2.

This should speed up the analysis somewhat.

This reverts commit 31d13675.