pynode: Simple bitcoin P2P node

Github URL: https://github.com/jgarzik/pynode

pynode is a simple bitcoin P2P client, based on ArtForz' half-a-node, which maintains a blockchain database and TX memory pool.

It is intended to be a useful base for another projects, such as network monitoring nodes.

At present, it is mainly for developers and not end users. Here is what pynode does NOT do:

*    RPC
*    key management (wallet)
*    script verification
*    chain re-org

Here are the limited things that pynode can do at present:

* Outgoing TCP connection to a single remote P2P node * Initial blockchain download * Maintain a transaction memory pool, with TX's removed as they are confirmed in blocks * Maintain an indexed blockchain database

Over time it will become more capable, but this is an alpha quality release for developers at present.

Contributions welcome! It is intended to become a full, wallet-less node over time (though if somebody wanted to contribute a wallet module, that is OK too)