Diamond shape

[FedericoPonzi]

Adds support for diamond shape.

[lecho]

Thanks:)

[FedericoPonzi]

You're welcome! :) Thanks for the great library! 👍

[lecho]

:)
btw. I found out that drawing square on rotated canvas(by 45 degrees) takes about the same time but is a little less code:

canvas.save();
canvas.rotate(45, rawX, rawY);
canvas.drawRect(rawX - pointRadius, rawY - pointRadius, rawX + pointRadius, rawY + pointRadius, pointPaint);
canvas.restore();

[FedericoPonzi]

Nice! :D