GitLab

adding donut type chart, like a pie chart with a blank circle on the center and little trick for label position (#111)

(some way of improvement)

* Add type classes on class output

Without this it is quite difficult to differentiate between fill and
stroke elements, f.e. with basic charts with fillings or legends
generally:
`svg path:nth-last-of-type(2).legend`

Text elements needed to be accessed with text.classname which
isn't really best practise.

This way they can be accessed easier:
`svg .legend.fill`

* Add type classes to examples

* Fix import in custom_stylesheets example

* Add ability to set custom stylesheets for SVG renderer

This allow to set custom inline CSS and a optional CSP nonce. This
solves the problem mentioned in #103 and is best used with it, as seen
in the added examples. Without this one would have to write a custom
renderer.

* Add note with link to the custom_stylesheets example

* Add ability to set CSS classes instead of inline styles

This allows to set a `ClassName` field in `Style` structs. Setting this
field to anything but "" will cause all other styles to be ignored. The
element will then have a `class=` tag instead with the corresponding name.

Possible reasons to use this:
* Including multiple SVGs on the same webside, using the same styles
* Desire to use strict CSP headers

* Add warning that setting `ClassName` will drop all other inline styles

* "Style{Show: true}" to "StyleShow()"
* "Box{IsSet: true}" to "BoxZero"

It seems that `RandomValuesWithMax` is correct.
https://github.com/wcharczuk/go-chart/blob/9e3a080aa3e7573281cf8d65a55305e1148d857d/seq/random.go#L15

* Fixed order of arguments to assert.Len in test files.

* Added BaseValue funtionality to bar chart

* Delete .DS_Store

* Update .gitignore w/ common exclusions

From https://github.com/github/gitignore/blob/master/Go.gitignore