* v1.5:
  PHPLIB-494: Fix validation of options with default values
  PHPLIB-494: Test against null for options with default values
  Simplify generator setup in tests
  PHPLIB-501: Use IteratorIterator to prevent memory leak with generators

* v1.5:
  PHPLIB-485: Inherit collection's typeMap in distinct
  PHPLIB-481: Add functional test for pipeline-style bulk updates
  PHPLIB-481: Remove duplicated bulk write tests
  PHPLIB-481: Add the ability to specify a pipeline to an update within bulk write

PHPLIB-485: Inherit collection's typeMap in distinct

PHPLIB-481: Add the ability to specify a pipeline to an update within bulk write

Replaced DBRef section with references to BSON class table footnotes. Re-ordered sections in order of importance (group helper is least relevant). Removes RST syntax for save flowchart image, which did not appear to work properly and also isn't necessary.

This also re-orders the section to appear before the Collection API changes.

PHPLIB-482: Add missing error expectation to crud tests