Make docs for running tests consistent with utils.inc
Merge branch 'pull-request/260'

* pull-request/260:
  Make docs for running tests consistent with utils.inc
Fixed PHP-621 (double free)

We need to copy the elements from cleanup_ids to the array passed to
->remove() so that we can free the returned array without messing up
the cleanup_ids array which is freed later.

The options array should also be freed after each call
Merged pull request #258
[PHP-638] Return constant string types in getReadPreference()

Replace numeric types with the constant string values and eliminate the irrelevant "type_string" field.

The change to mongo_read_preference_type_to_name() should also fix compatibility with mongos, as the "preferred" strings were not what the server expected in the cursor $readPreference mode.
[PHP-638] Test $readPreference modes for mongos cursors
[PHP-638] Make getReadPreference() tags consistent with those set
Merged pull request #259