Optimize numberToReturn for OP_GET_MORE based on the limit

If an application requests a limit that turns out to be great than the number of documents returned from OP_QUERY, the driver should adjust the numberToReturn value for the OP_GET_MORE to ensure that no more documents are returned by the server than necessary. Example with a limit of 105:

1. For OP_QUERY, set numberToReturn=105, and receive 101 documents in OP_REPLY (the driver already does this).
2. For OP_GET_MORE, instead of setting numberToReturn=105, set it to 4.