Support for custom empty element tag closing

[ethanjurman]

https://developer.mozilla.org/en-US/docs/Glossary/Empty_element

It's redundant and obnoxious to close custom elements that do not take in or make use of children elements. @JRJurman is this possible?

[JRJurman]

We should definitely look into this... The issue is either in https://github.com/Tram-One/bel-create-element or in https://github.com/aaaristo/rbel

[ethanjurman]

We could provide a function that checks for nested tags and properly closes them before sending to bel / rbel... but then the question is whether we are sacrificing performance for what would be a less than optimal solution.

Actually would the performance there really matter?

[JRJurman]

turns out it was hyperx, pr in the works: choojs/hyperx#58