Steem 0.14.3 Pre-release

This is a pre-release for Steem 0.14.3. This release includes bug fixes and a soft fork.

Documentation changes

• Change structure and update content of documentation / README.md #487
• Move list of seed nodes to its own file #487
• Update list of seed nodes #505

Functionality changes

• Add new API calls get_discussions_by_blog(), get_discussions_by_comments()
• Add first_reblogged_by field to get_state reply
• Record both SBD and STEEM post payouts in author_reward_operation
• Add ability to mine to debug_node #519
• Expose get_dev_key() function analogous to the get_dev_key binary in debug_node_api #519

Bugfixes

• Fix bug resulting in multicore mining attempting to mine the same nonces on each core #525
• Transactions downloaded from the network were not always verified when using checkpoints
• Softfork to forbid long account names in authorities #465
• Softfork to forbid using non-existing account names in authorities #465
• Update mining stats display to provide correct information for pow2 mining #282
• Fix bugs preventing creation of testnets #519
• Convert machine-length integer in chain state to fixed-length integer #485

Architecture changes

• Various changes to how Dockerfiles build and run the code
• Remove some unused code #511
• Remove unused ENABLE_CONTENT_PATCHING compile-time constant #510
• Update newplugin.py for new internal API #506