Add functionality to give pie & doughnut datasets a weight attribute, which affects the relative thickness of the dataset when there are multiple datasets in pie & doughnut charts. The default weight of each dataset is 1, providing any other numerical value will allow the pie or doughnut dataset to be drawn with a thickness relative to its default size.
For example a weight of 2 will allow the dataset to be drawn double its typical dataset thickness. Note that the weight attribute will only affect a pie or doughnut chart if there is more than one visible dataset. Using weight on a pie or doughnut dataset when there is only one dataset on the chart will have no affect.
`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}`.
The bar `backgroundColor`, `borderColor`, `borderWidth` and `borderSkipped` options are now scriptable (unit tests, docs and a basic sample). Also fix the gulp task that generates the documentation on Windows.
* 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"
When `barThickness: undefined|null` (default), we compute an optimal sample size based on the smallest tick interval reduced to prevent any bar to overlap (bar equally sized). Also added support for a special `barThickness: 'flex'` value (previous default) that globally arranges bars side by side to prevent any gap when percentage options are 1 (variable bar sizes).
