Aggregate::execute() already checks for this. This also adds a note in CollectionFunctionalTest that watch() is prohibited within a transaction, as is done for other methods.

This bumps the PHPC requirement to 1.5.2+, since that includes libmongoc 1.12 and CDRIVER-2744.

Since ext-mongodb 1.5.0 drops support for server 2.6, we can remove wire version checks and legacy code for servers before 3.0 (i.e. wire version 3).

PHPLIB-53 Add documentation for mapReduce

This ensures that the library's default type map (i.e. model classes) are used for manually constructed Database and Collection objects.

If we've learned anything from the legacy driver, it's that options arrays will prove more flexible than nullable, positional arguments in the long run.

See: PHPC-444, HHVM-117

Also use assertEquals(), since assertSame() tests for object identity.