Nodeps: Support deep nested structures for mapMultiRowFields

[ocordeiro]

Add Support to deep nested structures for mapMultiRowFields
without new dependencies.

[coveralls]

Coverage remained the same at 100.0% when pulling d788ab1 on ocordeiro:master into 886c135 on maoberlehner:master.

[geoidesic]

@ocordeiro Please update / add tests for this PR.

[geoidesic]

This doesn't seem to be backwards compatible btw. I.e. I've tried it with existing code that works with mapMultiRowFields and that breaks with this implementation. Specifically, it doesn't allow the final end node to be an array (some elements like select require the model to be an array) – if it is an array then it assumes that array is intended to be part of nested iteration and will iterate into that array. So as far as I can tell this cannot be used with such elements, which makes this largely useless. I've tried to implement this in various ways and I can't see that it's doing anything useful. @ocordeiro perhaps it would help if you could show a usage example, obrigado! The ball is in your court.

[ocordeiro]

This doesn't seem to be backwards compatible btw. I.e. I've tried it with existing code that works with mapMultiRowFields and that breaks with this implementation. Specifically, it doesn't allow the final end node to be an array (some elements like select require the model to be an array) – if it is an array then it assumes that array is intended to be part of nested iteration and will iterate into that array. So as far as I can tell this cannot be used with such elements, which makes this largely useless. I've tried to implement this in various ways and I can't see that it's doing anything useful. @ocordeiro perhaps it would help if you could show a usage example, obrigado! The ball is in your court.

added tests and synced with latest release