- New upstream release 1.7.0
- https://github.com/less/less.js/blob/v1.7.0/CHANGELOG.md
- Add support for rulesets in variables and passed to mixins to allow wrapping
- Change luma to follow the w3c spec, luma is available as luminance. Contrast
  still uses luma so you may see differences if your threshold % is close to
  the existing calculated luma.
- Upgraded clean css which means the --selectors-merge-mode is now renamed
  --compatibility
- Add support for using variables with @keyframes, @namespace, @charset
- Support property merging with +_ when spaces are needed and keep + for comma
  separated
- Imports now always import once consistently- a race condition meant
  previously certain configurations would lead to a different ordering of
  files
- Fix support for `.mixin(@args...)` when called with no args (e.g.
  `.mixin();`)
- Do unit conversions with min and max functions. Don't pass through if not
  understood, throw an error
- Allow % to be passed on its own to the unit function e.g. `unit(10, %)`
- Fix a bug when comparing a unit value to a non-unit value if the unit-value
  was the multiple of another unit (e.g. cm, mm, deg etc.)
- Fix mixins with media queries in import reference files not being put into
  the output (they now output, they used to incorrectly not)
- Fix lint mode- now reports all errors
- Fixed a small scope issue with & {} selector rulesets incorrectly making
  mixins visible- regression from 1.6.2
- Browser- added log level "debug" at 3 to get less logging, The default has
  changed so unless you set the value to the default you won't see a
  difference
- Browser- logLevel takes effect regardless of the environment (production/dev)
- Browser- added postProcessor option, a function called to post-process the
  css before adding to the page
- Browser- use the right request for file access in IE