Release Candidate 1 - Zetacoin 0.12.0

This is a release candidate for an upgrade to the 0.12.0 base.

Please report any issues on GitHub.

Users who compile from source can use the 0.12.0-rc1 branch.

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 a full list see:

https://github.com/zetacoin/zetacoin/blob/0.12.0-merge/doc/release-notes.md

For binaries see:

https://github.com/zetacoin/zetacoin/releases/tag/v0.12.0-rc1