chart-element samples missing

[goessner]

Make examples to demonstrate usability

[klawr]

First example provided in 5f15bf0.
g2.chart is accepting functions (e.g. Math.sin), which is not supported by JSON.

We could add some kind of parsing here, for example the ability for g2.chart to accept strings like "sin", "cos", "PI" etc. to be handled accordingly.

[goessner]

The most simple way here would be to use eval ... but it's evil.

I also would like to have normal strings in JSON data and interprete them like template strings.

I once read a discussions about that:

https://stackoverflow.com/questions/29182244/convert-a-string-to-a-template-string
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#Never_use_eval!

The Function related solution sounds promising ... try it.