Save sketches as static images
Dear Dev,
first, let me thank you for this fantastic library.  At the risk of asking something potentially trivial, I would like to know whether it is possible to save sketches as static images e.g. png. I am a researcher and I am very interested in using Sketch to programatically generate diagrams and graphics to (i) share my research results; and (ii) teach some Computer Science modules. I am new to Lisp, and so, again, I might be asking something very basic. Unfortunately, I could not find an answer to my question by looking at Sketch's source code.  Or maybe this is not a correct use case for Sketch?
 I will be very happy if you could give me some pointers. 

Thanks for your efforts.

Nery
