P2pool util forest

This contains code for tracking shares.

Class Tracker

Number of dictionaries that store the shares in various ways to allow fast access.

1. shares (hash->share) Since share contains parent share allows you to link to previous shares all the way to the tail.
2. reverse_shares (delta.tail->set of share_hashes) Allows you to link share to the next share that came after it all the way to the head.
3. deltas (share_hash -> delta, ref)
4. reverse_deltas (ref -> set of share_hashes)
5. delta_refs (ref -> delta)
6. reverse_delta_refs ( delta.tail -> ref)

what are deltas??? I have not got my head round this code at all!

Method add

Adds a share to the tracker