* PHPLIB-276 Change stream support

* PHPLIB-297 Support maxTimeMS option for DropIndexes operation

* PHPLIB-254 Support maxTimeMS option for CreateIndexes operation

* PHPLIB-293 Add support for a comment parameter to the aggregate command

The call is made following the MongoDB\Client::selectCollection() signature instead of the MongoDB\Database::selectCollection() signature

The call is made following the MongoDB\Client::selectCollection() signature instead of the MongoDB\Database::selectCollection() signature

The call is made following the MongoDB\Client::selectCollection() signature instead of the MongoDB\Database::selectCollection() signature

This will allow the returned CollectionInfoIterator and IndexInfoIterator classes to be rewound and iterated multiple times.

Ensure that a call to CachingIterator::rewind() no longer exhausts results up front, which would impose a BufferedIterator design.

Initializing the cache to an empty array also ensures that we can count an empty result set.

On servers before 3.2, the option is ignored, which results in a noticeable delay while running the test suite.

This class was originally added in PHPLIB-112

PHPLIB-284 Highlight API changes in documentation