Split up StatusDeque into different modules
* LastIdQueue tracks last_ids
* StatusCache keeps track of signature statuses
* StatusCache stores success as a bit in a bloom filter
* Overhead for 1m Ok transactions is 4mb in memory
* Less concurrency between the objects, last_id and status_cache are read and written to at different points in the pipeline
* Each object has its own strategy for merging into the root checkpoint
Greg Fitzgerald
anatoly yakovenko
Michael Vines