Add an additional visualization backend - weas #4
Description
weas (https://github.com/superstar54/weas), developed by @superstar54 might potentially be a better visualization backend than the currently used 3dmol.js (which is mainly meant for molecules and also biological applications, not crystals). for example, weas support polyhedra, while 3dmol does not.
Initially, weas could be added as a additional visualization backend, such that the user could choose either, and eventually one can be dropped.