Zetacoin 0.12.0.1 - Major code upgrade

Notable changes:

- Signature validation using libsecp256k1
- Direct headers announcement (BIP 130)
- Automatically use Tor hidden services
- Notifications through ZMQ
- Wallet: Pruning
- Mining Code optimizations

For downloads see:

https://github.com/zetacoin/zetacoin/releases/tag/v0.12.0.1