Support Entities

[florianm]

Build should support entities as per the XForms spec on entities.

Reasons to implement

Entities are a major bonus feature for prospective and existing ODK users, and providing that feature directly in Build would make it accessible to newcomers and low code users.

Reasons for not implementing it yet

Low available developer bandwidth (at least from my end) while allowing the spec to mature.

Assumptions

• XForms spec for entities is (close to) stable.
• Entity support in Build is desirable to Build users.
• There are no plans to abandon Build in the near future, so that the implementation effort would be worthwhile.