[Feature request]Implement optional checkboxes for multiple items data types

[enfJoao]

I'm submitting a

[x] feature request

...about

[x] Content Types or data management

2sxc currently uses it's own UI to select multiple items in a field, such as entity data type. This allows nice features such as retaining order.
It's also very slow and complex because you need to enter a new menu to select the items in a dropdown environment, one by one.

One alternative, optional and configurable would be a good old checkboxes. Stored in the exact same way that the string dropdown or entity are.

[iJungleboy]

I feel like this could be useful.

We've been working in the background for a completely new "Picker" infrastructure as we see a lot of things we could improve there. I assume we'll release that in ca. 8 weeks and maybe this could make it as well :).