Support __next field in response for partial listing

[phanak-sap]

In response payloads, representing Collections of Entries, if the server does not include an object for every Entry in the Collection of Entries identified by the request URI then the response represents a partial listings of the Collection. In this case, "__next" name/value pair is included to indicate the response represents a partial listing. The value of the name/value pair is a URI which identifies the next partial set of entities from the originally identified complete set.

• [x] Experimental API (intentionally not part of Changelog and Documentation) - PR #188
• Example: employees = northwind.entity_sets.Employees.get_entities().next_url(employees.next_url).execute()
• [x] Document as official API or rewrite. Check comments from PR#188 for details
• [ ] Confirm stable status (changelog, doc update) or find more "pythonic" way for subsequent pagination requests

[rettichschnidi]

PR #188 got merged

[phanak-sap]

This is year out, no better alternative explored so far, committing to be in the 1.X version as is.