Include Energy Systems Language shapes#353

Energy Systems Language is a set of shapes used in some fields of Ecology to represent the flows of matter or energy and display their efficiency. I have not seen those in any diagramming software and should be relatively easy to implement to give an edge in the market.

Hi @Javert 8,

Thank you for brining this to our attention. This will is indeed be a great addition to the library. We will look into this asap.

Thank you