FIX: In JSON, viewpoints should include items and highlights.

Regression introduced by commit 4e2e6d91acce08cd002b00533a6aa29df279504e.
Merge branch 'fix-viewpoint'
REFACTORING: Reduced memory use when sending JSON.
REFACTORING: Remove unused data from JSON payloads.

Included "docs" are only useful for HTML payloads.