* 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
* Early data parsing + stacking by value
* Review comments
* review comments
* Remove reduntant parsing
* Couple CC warnings
* Optimize filterBetween
* More migration info
`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}`.
* added 'angle' option to polar charts. image comparison test is work in progress; not currently passing
* removed unnecessary variable assignment
* code cleanup based on PR; for 'angle' option on polarCharts
* Made polar chart image comparison test pass by removing debug flag. Also explicitly marked _computeAngle as private.
* Removed visibleCount computation in polar chart
* split out code related to updating the radius in polar chart's update function, into it's own 'updateRadius' function
* made updateRadius method private
* fix linting error
* updated polar charts to read custom angles from "chart.options.elements.arc.angle" instead of "chart.options.angle"
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).
Properly export helpers and remove dependencies to `Chart.helpers`. Helpers can now be accessed from `src/helpers/index.js` (`var helpers = require('path/to/helpers/index')`, instead of `var helpers = Chart.helpers`).
For consistency with `valueOrDefault`, `valueAtIndexOrDefault` now returns null if `value` (expected array) is null. Also get rid of the superfluous `get` prefix in `getValueOrDefault` and `getValueAtIndexOrDefault`.
gridLines.circular is a new option that toggles circular lines. This allows radar charts with circular lines #3082
pointLabels.display is a new option that toggles the display of point labels.
The existing angleLines.display is used with the new pointLabels.display setting is used to trigger the radar like settings.
This required changing the default polar area config.
This change allows for smaller minified code in the final version, resulting in a smaller file size. Some files had previously used _this, but that has been changed to me to keep consistency throughout the project.
Data controllers should now rarely implement addElements and addElementAndReset but instead should define dataElementType (and optionally datasetElementType). Also remove some dead code (e.g. numBars, colorForNewElement, etc.).
