* Add support for description in fixtures
* Update datasetController to draw active(s) last
* Handle hiding of line by borderWidth
* Disable filling of scatter charts by default
* Make radar chart consistent with line
* Convert axis options from arrays to objects
* Updated all chart type defaults
* Throw errors when axis type or position are not specified
* Avoid raising unnecessary errors when merging options into the default configs
* Fix additional tests
* Ensure scale defaults are set if type is not explicitly defined
* Another step
* Include `scale` as `firstIDs.r`
* update docs
* Update for buildOrUpdateScales
* Update migration guide
* Add test back
`controllers.*.js` and `core.datasetController.js` are now importable (no more function export), that's why there is so many changes mainly due to one indentation level removed. Split code for `bar/horizontalBar` and `doughnut/pie` in separate files, added a global controllers import (`src/controllers/index.js`) and add tests to check that all dataset controllers are correctly registered under `chart.controllers.{type}`.
Default options can now be accessed by importing `core/core.defaults`. The returned object acts as a singleton and is populated when importing classes that expose their own default values (meaning that importing only `code.defaults` results in an empty object). Also make `Chart.Ticks` and `Chart.Interaction` importable since existing defaults rely on these values.
Add the `defaults._set` method that make easier declaring new defaults by merging given values with existing ones for a specific scope (`global`, `scale`, `bar`, etc).
