cht: add Chart.apply_template()

[chvolk]

Hi,

I want to use a custom chart template in your library instead of the default Pie chart template. I was wondering if you could point me to a place in the library where I can manually insert my chart's template. Any help would be appreciated!

I have checked out the chart_style function, but what I need is to load in my own custom template (uses select colors and has custom spacing and such)

[scanny]

There's no API support for chart templates yet.