Merge commit '32983b8dc5e35871f5982bf607a4eac3c708b15e'

* commit '32983b8dc5e35871f5982bf607a4eac3c708b15e':
  Squashed 'vendor/assets/javascripts/d3/plugins/' changes from fc984ac..40b96be
Squashed 'vendor/assets/javascripts/d3/plugins/' changes from fc984ac..40b96be

40b96be Update README.md
6b50944 Update README.md
fecbc79 Optimize.
8d92702 Shorten.
43591cc Restore example.
98f4ee3 Remove horizon.duration.
129d925 Default saturation is 50%.
6414ce3 Update documentation.
03791c5 Update documentation.
67d77dc Update documentation.
7ae22d3 Update documentation.
7914768 Update documentation.
cd48d3c Update documentation.
341941a New API.
cb5b568 Note about saturation.
c120e79 Fix documentation.
eb9dc14 Another example.
e0d6b0d Formatting.
bc9d113 Clarify mapping from original scheme.
e92e4fe Fix off-by-one.
de6aac8 Add d3.scale.cubehelix plugin.

git-subtree-dir: vendor/assets/javascripts/d3/plugins
git-subtree-split: 40b96be98bf10167fbe6ef77fa52ad87668cad99
Bump gem version
Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 40b96be..c64935b

c64935b Merge remote-tracking branch 'hongtaobai/master'
65730dc Fix memory usage issue caused by adding same node multiple times
6400fd4 Fix horizon.defined for non-default accessors.
39ad7c9 Add horizon.{defined,tension}.
0fde115 Typo in README.md

git-subtree-dir: vendor/assets/javascripts/d3/plugins
git-subtree-split: c64935bf2a6d0d9c799820f70c043e72530b8612
Merge commit '308bedd33bc11564ffb9b765db0b5b667fb1bde9'

* commit '308bedd33bc11564ffb9b765db0b5b667fb1bde9':
  Squashed 'vendor/assets/javascripts/d3/plugins/' changes from 40b96be..c64935b
Bump js version