Zcash Overwinter network update 1.1.1 released

Zcash Overwinter network update

Zcash 1.1.1 is overwinter compatible version of Zcash node software that has initial support for upcoming Sapling consensus that is slated to be activated in September 2018. It will also activate Sapling testnet at the block 252500. The Overwinter network update will be happening on 25th of June 2018 when the block 347500 will be mined.

Consensus code preparations for Sapling network upgrade are finished and included in this release. Sapling support in wallet and RPC is yet to be implemented in next few weeks from now.

Once the Sapling is activated, all transactions must make use of the new v4 format, including coinbase transactions. All RPC methods that create new transactions will create v4 transactions as well.

Changelog:

* set the Sapling testnet activation height to block 252500.
* removed the 100kB transaction size limit from Sapling activation.
* implemented Sapling consensus rules.
* implemented Sapling merkle tree, nullifiers and added supported for v4 transactions and loading Sapling parameters.
* implemented ZIP 243 for Sapling signature hashing.
* updated support for Sprout shielded transactions to use the Groth16 proving system when Sapling activates.
* backported transparent address refactors, and are in the process of adding support for Sapling keys, addresses and notes.
* extended a mempool eviction RPC test to cover Sapling activation.
* backported improvements to RPC call getblock.
* updated the Payment API documentation.
* resolved Least Authority auditor issues C, D and E.
* updated the build process to use Rust 1.26 stable.
* fixed bugs on several unsupported platforms.
* extended Sprout tests to other epochs.
* backported improvements to zcash-cli, serialization, out-of-memory error reporting and the configuration option uacomment.