refs #969, add uassert for initializer that converts a normal collection to partitioned, and a comment explaining why we are currently limiting that functionality, disabling functionality for now
refs #1024 Get query and sort info down the stack.
refs #1024 create a SubCursorGenerator class, and remove some of this functionality from PartitionedCursor
refs #1024, create new SubPartitionIDGenerator class. Further simplify PartitionedCursor class
fix some tests from work done so far on Partitioned Collections, unrelated to this change
refs #1024 move PKDupSet to cursor.h, it will come in handy
refs #1024, implement SortedPartitionedCursor, it is now passing hand tests and looks done. Needs automated tests
refs #1024 implement the FilteredPartitionIDGeneratorImpl, allows for queries on secondary indexes to not visit all partitions, similar to how sharding does not visit all shards for a query
refs #1024, support multikey cursors on partitioned collections
refs #1024 add test for cursors on secondary indexes, verifying correctness and that proper filtering of partitions is done
make a special case for when there is just one partition to query, to not use a SortedPartitionedCursor