Refactoring into an ECS architecture

[stephanemagnenat]

Enki has reached its complexity limit with its current design. After a discussion with @dmiklic, we think it should be refactored into an Entity Component System (https://en.wikipedia.org/wiki/Entity_component_system), as this approach has proved successful in the game industry.

[stephanemagnenat]

Draft proposal for new design:
new-design.txt

[dmiklic]

@plsm and myself have started putting together a class diagram of the new architecture, in order to better understand it. So far, we've tried to transfer the document attached above to a diagram that can be accessed here.

It's done in draw.io, which is quite a pain to work with, so if you have a better suggestion, please let us know :)