Add ctrie binary to gitignore
Add initial working single-thread insert/update/lookup/delete

    * Refactor lnode implementation
    * Add delete for kv in cnode and lnode
    * Test with 2^20 keys
Merge branch 'feature/delete'

* feature/delete:
  Add initial working single-thread insert/update/lookup/delete
  Add ctrie binary to gitignore
Update README