4.0.0-rc.0

- Breaking: Drops support for Node 0.12, we now require at least Node 4.
- Breaking: Update PostCSS to 6.0.0.

# 2.1.0

- Now supports discarding duplicates irrespective of property order, better support for legacy hacks & partial duplicate removal (thanks to @andyjansson).

# 2.0.2

- Major performance boost by lessening algorithmic complexity; each node is now cached and the nested loop removed, meaning that each node is cast to a string only once (thanks to @asztal).

# 2.0.1

- Now compiled with babel 6.
- Minor performance boost from exiting from the `dedupe` function if the node has less than two child nodes.

# 2.0.0

- Upgraded to PostCSS 5.

# 1.2.1

- Fixes an integration test failure with cssnano; use PostCSS `each` rather than native `forEach` (thanks to @TrySound).

# 1.2.0

- Improved duplicate detection (thanks to @TrySound).

# 1.1.6

- Improved performance by caching string representations of nodes, and minimising stringifying as much as possible (thanks to @TrySound).

# 1.1.5

- Fixed an issue where comments were being deduplicated.

# 1.1.4

- Improved performance by making all AST iterations in a single pass.

# 1.1.3

- Improved documentation for compatibility with the plugin guidelines.
- Simplify main source code.

# 1.1.2

- Fixed an issue where declarations inside similar keyframes were being discarded incorrectly.

# 1.1.1

- Fixed a bug where keyframe rules were being incorrectly discarded, if they had the same declarations but different vendor prefixes.

# 1.1.0

- Now uses the PostCSS `4.1` plugin API.

# 1.0.0

- Initial release.