This changes the behavior of `autoSkip` so that it does not force the
display of the last tick. If the last tick can be displayed with equal
spacing to the rest of the ticks, it will be. Otherwise, it is not.
- Remove `Math.round` in the category scale code
- Add `helpers._alignPixel` to align grid/tick/axis border lines
- Fix grid/tick/axis border line calculation
- Add a check of the width of the axis border
- Refactor core.scale code
JSON doesn't support functions which are needed to create scriptable options, so implement a very basic method to load a JavaScript file exporting the config in `module.exports`. Also rename test sources (remove the `jasmine.` prefix), cleanup `karma.conf.js` and add an example .js fixture config (bubble radius option).