simplay / simplay-web: smooth movement of entities

[moschi]

Currently, entities "snap" from position to position. It might be useful to have smooth animated movement of entities.
For this, API in simplay would need to be added, and functionality to consume the created events in simplay-web would need to be created.

DoD:

• idea is elaborated and discussed
• a proposal exists of how to implement the feature, or it’s decided to not do it
• follow up tasks created