Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 639c06c..3738859

3738859 Remove transverse Mercator; now in 3.1.0.
8698a7b Minor optimisation.
c63b4d6 Add d3.geo.gallStereographic.
b9f162c Add Gall’s stereographic projection.
2f819e4 Update README.md
658ce50 Update README.md
ca6049d Fix markdown formatting in README.
5ada3d5 More minor code cleanup.
56f25a3 Add missing semicolons.
5caed3e Update uglify-js.
8569b45 Fix d3.geo.berghaus sphere outline.
5be6150 Remove conic projections now in 3.1.0.
d3a679c Remove obsolete d3.simplify plugin.

git-subtree-dir: vendor/assets/javascripts/d3/plugins
git-subtree-split: 37388598a7fd9865f6ffddeefcad16a5d039b4bb
Merge commit '22aa01ffbcde03905430d2872b5d8840402f9c92'

* commit '22aa01ffbcde03905430d2872b5d8840402f9c92':
  Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 639c06c..3738859
Bump bundled d3 plugins js