Chainweb

This version replaces all previous versions. Any prior version will stop working
on **2020-04-30T00:00:00Z**. Node administrators must upgrade to this version
before that date.

This version will stop working on **2020-06-11T00:00:00Z**.

* Starting with block height 530500 the first eight bytes of each block must be
set to zero. (974)

* The option to persist the peer database is removed. The functionality
was rarely used and can be simulated by using the peer REST API endpoints
along with the know peers configuration option. (1010)

* Removed the PUT endpoints from the `/chain/header` APIs. (1002).

* Make block header validation aware of adjacent parents. (1004).

* Increased the default block gas limit by 10x to 150,000. Note that if you
have manually specified a block gas limit in your node config file, this
change will not take effect. We recommend removing it and using the
chainweb-node default. (1019).

This version replaces all previous versions. Any prior version will stop working
on **2020-04-02T00:00:00Z**. Node administrators must upgrade to this version
before that date.

This version will stop working on **2020-04-30T00:00:00Z**.

The use of the first eight bytes of the mining jobs bytes as nonce is now
considered deprecated. Those bytes should be set to 0x0. Only the last eight
bytes must be used as nonce. Miners and pools should start upgrading to the new
behavior. The new behavior will be enforced in a future version.

* Compute epoch time based on parent header. This change won't affect any
any users of Chainweb. The change will become effective at block height
452820. (977)

* Validate transaction creation time and expiration with respect to creation
of the parent block header. This change brings the checks for transaction
validity in line with the time used during Pact validation. (935, 942)

There is a 90 second leniency applied for transactions to become valid. This
change will become effective at chain block height 449940. In the time before
the change becomes active users may experience that new nodes reject their
transactions. This can be mitigated by using a negative offset for the
creation of about 2 minutes. (973)

* A new flag `--allowReadsInLocal` and configuration option was added that
enables direct database reads of smart contract tables in local queries.
(938)

* Fixed a rare bug that could affect nodes during history rewinds. (940)

* Internal CPU mining use the last eight bytes of the mining jobs bytes as nonce
(957)

* Add missing `cut` API to the swagger documentation of the Chainweb API (980)

* Fixes a bug that caused Chainweb nodes to crash during startup due to running
out of RAM. (982)

* Beside several stability and performance improvements this release
also greatly improves test coverage and the quality of the code base to
support long term maintainability of the Chainweb codebase.

This version replaces all previous versions. Any prior version will stop working
on **2020-02-20T00:00:00Z**. Node administrators must upgrade to this version
before that date.

This version will stop working on **2020-04-02T00:00:00Z**.

* Adds enriched message body to gas payer execution (912)

* Pact fix for enforce-one, guards runtime TC (916)

* Gas perf improvements (871)

* Remove custom `systemd` usage (908)

* Mine an additional cut height in SPV tests (889)

* Add configuration options for checking payload hashes during pact replay (903)

* pact: poll: report when a transaction is on the bad list. (842)

* More detailed errors when attempt buy gas fails (893)

* Fix performance of applyRank (892)

* improve performance of branchEntries (885)

This version replaces all previous versions. Any prior version will stop working
on **2020-01-15T00:00:00Z**. Node administrators must upgrade to this version
before that date.

This version will stop working on **2020-02-20T00:00:00Z**.

* Full launch of Pact smart contract functionality (begins at
2020-01-15T16:00:00Z)

* Increased block gas limit to 15000 (870)

* Minimal SPV proofs are created by default (affects cross-chain transfer proof size) (860)

* Enriched results at /poll and /listen endpoints (866)

* Caching improved for coinbase transactions (861)

* Improvements to node stability and node stalling issues (844, 845)

This version replaces all previous versions. Any prior version will stop working
on **2019-12-17T00:00:00Z**. Note administrators must upgrade to this version
before that date.

This version will stop working on **2020-01-15T00:00:00Z**.

* All nodes in the miners list in the configuration file are served cached work
[819]

* Correct account balances that where compromised by vulnerability 797.
The adjustment will occur in the first block with a creation time after
2019-12-17T15:00:00Z on the respective chains. [830]

* Avoid opening and closing the pact SQLite database after pact validation
errors. [817]

* [SECURITY] fix issue with date comparison triggering block validation of fix for 797 [810]

* Don't vacuum SQLite databases on startup [803]