Adding color to model

Hi @sime we're happy to receive contributions to this module. So, if you wanted to start with an issue fork and create an MR, I'm more than happy to review and later merge that into the product.

Please let me know if you needed any assistance in understanding how the webpack application is brought together. Which is need to add more components to it. Also, let's consider to make this new feature optional, i.s. should users be able to enable it, when it's disabled by default?

That is really good to know. I'll leave this open for when i have a chance to dive deeper.

Moving this to the 3.x branch.

There is now a color picker for elements. This is only available in version 3 and later, and at this point, the color will only be stored in the raw data of the model, not in the model owner config enttities.