Tracking: Basic SSTable Implementation.

[MrCroxx]

Tracking:

• [x] Block encoding.
• [x] Block decoding.
• [x] Varint encoding.
• [x] SSTable data object encoding.
• [x] SSTable data object decoding.
• [x] SSTable meta object encoding.
• [x] SSTable meta object decoding.
• [x] Binary search on single block.
• [x] Block iterator.
• [x] Contact iterator.
• [x] SSTable iterator (depends on SstableStore and ObjectStore).
• [x] Merge iterator.
• [x] User key iterator.
• [x] Tombstones.
• [x] User key iterator with tombstones.

[MrCroxx]

Close. 🎉

[MrCroxx]

Forgot to implement tombstone, reopen, orz.

[MrCroxx]

Close via #32 .