Chunking (#10)

* Add checkenc without serialisation for now.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Simplify interface and add serialisatio`

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Move away from \xFF magic to something simple

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Add serialisation and Deserialisation

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Modify interface to be closer to logish interface.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* chunkenc: Fix race b/w append and iteration.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* chunkenc: Make iterators honour bounds

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* chunkenc: Remove locks as safety is assured externally

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* chunkenc: Add checksums

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Add code quotes around block design.

* Split headBlock into it's own type.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Simplify encoding and decoding.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

* Expose flags.

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Use the already existing EntryIterator interface

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Use existing Chunk interface.

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Review feedback

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Integrate the compressed chunk and add metrics

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>