Bugfixes

• (Attempt to) Fix deadlock between consumer and heartbeat (zhgjun / dpkp #1628)
• Fix Metrics dict memory leak (kishorenc #1569)

Client

• Support Kafka record headers (hnousiainen #1574)
• Set socket timeout for the write-side of wake socketpair (Fleurer #1577)
• Add kerberos domain name config for gssapi sasl mechanism handshake (the-sea #1542)
• Support smaller topic metadata fetch during bootstrap (andyxning #1541)
• Use TypeError for invalid timeout type (jeffwidman #1636)
• Break poll if closed (dpkp)

Admin Client

• Add KafkaAdminClient class (llamahunter #1540)
• Fix list_consumer_groups() to query all brokers (jeffwidman #1635)
• Stop using broker-errors for client-side problems (jeffwidman #1639)
• Fix send to controller (jeffwidman #1640)
• Add group coordinator lookup (jeffwidman #1641)
• Fix describe_groups (jeffwidman #1642)
• Add list_consumer_group_offsets() (jeffwidman #1643)
• Remove support for api versions as strings from KafkaAdminClient (jeffwidman #1644)
• Set a clear default value for validate_only/include_synonyms (jeffwidman #1645)
• Bugfix: Always set this_groups_coordinator_id (jeffwidman #1650)

Consumer

• Fix linter warning on import of ConsumerRebalanceListener (ben-harack #1591)
• Remove ConsumerTimeout (emord #1587)
• Return future from commit_offsets_async() (ekimekim #1560)

Core / Protocol

• Add protocol structs for {Describe,Create,Delete} Acls (ulrikjohansson #1646/partial)
• Pre-compile pack/unpack function calls (billyevans / jeffwidman #1619)
• Don't use kafka.common internally (jeffwidman #1509)
• Be explicit with tuples for %s formatting (jeffwidman #1634)

Documentation

• Document connections_max_idle_ms (jeffwidman #1531)
• Fix sphinx url (jeffwidman #1610)
• Update remote urls: snappy, https, etc (jeffwidman #1603)
• Minor cleanup of testing doc (jeffwidman #1613)
• Various docstring / pep8 / code hygiene cleanups (jeffwidman #1647)

Test Infrastructure

• Stop pinning pylint (jeffwidman #1611)
• (partial) Migrate from Unittest to pytest (jeffwidman #1620)
• Minor aesthetic cleanup of partitioner tests (jeffwidman #1618)
• Cleanup fixture imports (jeffwidman #1616)
• Fix typo in test file name (jeffwidman)
• Remove unused ivy_root variable (jeffwidman)
• Add test fixtures for kafka versions 1.0.2 -> 2.0.1 (dpkp)
• Bump travis test for 1.x brokers to 1.1.1 (dpkp)

Logging / Error Messages

• raising logging level on messages signalling data loss (sibiryakov #1553)
• Stop using deprecated log.warn() (jeffwidman #1615)
• Fix typo in logging message (jeffwidman)

Compatibility

• Vendor enum34 (jeffwidman #1604)
• Bump vendored six to 1.11.0 (jeffwidman #1602)
• Vendor six consistently (jeffwidman #1605)
• Prevent pylint import errors on six.moves (jeffwidman #1609)