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.).
Updated all chart types to use the helper.getHoverColor. Pattern fills can now be specified for both fill and line portions of a chart. Updates chartjs/Chart.js#1323
* Horizontal bar chart type
* Mentioned horizontal bar chart in bar documentation
* Sample file for horizontal bar chart
* Missing semicolon
* Fix for borderSkipped index
Introduced a new meta.hidden 3 states flag (null|true|false) to be able to override dataset.hidden when interacting with the chart (i.e., true or false to ignore the dataset.hidden value). This is required in order to be able to correctly share dataset.hidden between multiple charts.
For example: 2 charts are sharing the same data and dataset.hidden is initially false: the dataset will be displayed on both charts because meta.hidden is null. If the user clicks the legend of the first chart, meta.hidden is changed to true and the dataset is only hidden on the first chart. If dataset.hidden changes, only the second chart will have the dataset visibility updated and that until the user click again on the first chart legend, switching the meta.hidden to null.
Dataset effective type is now stored under meta.type, allowing many charts to share the same dataset but with different types. Also move dataset.bar flag to meta.bar.
Meta info are now scoped by chart and moved under the dataset._meta map { chart.id -> meta }. Meta for a specific chart (and dataset) can be accessed using chart.getDatasetMeta(datasetIndex) or from the dataset controller using getMeta(). Note that helpers.uid() now generates an int (instead of a string) to make lookups in the _meta map faster.
