Some additions are needed to draw oblique lines by clicking

I love very much your plugin and also chart.js.

But i think that for a better user experience some additions are needed.

**I'm talking about that on a financial plugin users should be able to click on the graph and draw slanted lines, equidistant channels and linear regressions from point to point.**

That's a very important think.

Other than that, congratulations and great job.
It's a real spectacle to see and the time saved is a lot.

Thanks