Squashed 'vendor/assets/javascripts/d3/plugins/' changes from c690548..a3c809c

a3c809c Fix token replacement in jsonp plugin
51a5ef2 Save a few lines.
53b6425 Add d3.geo.gringorten.invert.
611a10a Update geo/projection/README.md
443431c Reuse quincuncial for Gringorten.
f837048 Fix quincuncial inverse when no inverse is defined.
77f0b92 Split out quincuncial projection code.
2c461f9 Fix NaNs in d3.geo.vanDerGrinten4.
3220650 Add tests for d3.geo.healpix.
a93a7bd Add d3.geo.healpix.invert.

git-subtree-dir: vendor/assets/javascripts/d3/plugins
git-subtree-split: a3c809c32282be9980f24a1c7a08f7be6a3460c7
Merge commit 'cba711cd0a94f7af1af920557925a000c36a99d9'

* commit 'cba711cd0a94f7af1af920557925a000c36a99d9':
  Squashed 'vendor/assets/javascripts/d3/plugins/' changes from c690548..a3c809c
Bump gem version