* Contrib: use zstd, lz4 as submodule

* fix shared build

* re-test me.

* wip

* Update CHANGELOG_RU.md

* Update CHANGELOG.md

* Update CHANGELOG_RU.md

* Whitespaces [#CLICKHOUSE-2].

* Implemented TODO [#CLICKHOUSE-2].

* Whitespaces [#CLICKHOUSE-2].

* Remove wrong test

* Implemented TODO [#CLICKHOUSE-2].

* Moved chown to correct place [#CLICKHOUSE-2].

* Resolves #1273. Exception safe users update. [#CLICKHOUSE-3]

* Less noisy logging. [#CLICKHOSUE-2]

* Add metrics for RWLockFIFO. [#CLICKHOUSE-3246]

* Executable dictionaries: fail if program returns non zero exit code (#CLICKHOUSE-3171)

* Add better logging if OPTIMIZE cannot be executed. [#CLICKHOUSE-2]

* test me

* Fixing documentation fragment about "default" user. It is not mandatory anymore.

* append yurial/clickhouse-client to docs/interfaces

* Fixed FREEZE PARTITION: using only active data parts; acquire snapshot of parts [#CLICKHOUSE-3369].

* Removed tcp_ssl_port by default [#CLICKHOUSE-2].

* Update MergeTreeDataMerger.cpp

* Update ShellCommand.cpp

* Disable part sendings and fetches before ALTER. [#CLICKHOUSE-3343]

* Update ExecutableDictionarySource.cpp

* Update ExecutableDictionarySource.cpp

* Miscellaneous changes after merge [#CLICKHOUSE-2].

* Improve tests: allow redefine some values (clickhouse path, ports, ...)

* Received signal Segmentation fault (#1300) (#1302)

* Received signal Segmentation fault (#1300)

* Add test

* Tests: Use new possibly redefined values from env (in 2 tests)

* Proper fix for the issue: better exception message [#CLICKHOUSE-2].

* Split GatherUtils.cpp for faster compile (#1312)

* Split GatherUtils.cpp for faster compile

* remove GatherUtils.cpp

* Fix array writing (#1314)

* changed MergedBlockOutputStream [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* disabled checkNoMultidimensionalArrays [#CLICKHOUSE-3341]

* fix IMergedBlockOutputStream::writeDataImpl [#CLICKHOUSE-3341]

* fix IMergedBlockOutputStream::writeDataImpl [#CLICKHOUSE-3341]

* fix IMergedBlockOutputStream::writeDataImpl [#CLICKHOUSE-3341]

* fix IMergedBlockOutputStream::writeDataImpl [#CLICKHOUSE-3341]

* added test [#CLICKHOUSE-3341]

* fixed test [#CLICKHOUSE-3341]

* refactoring and comments [#CLICKHOUSE-3341]

* fix build [#CLICKHOUSE-3341]

* Update ColumnArray.h

* Update ActionBlocker.h

* Fix section tabulation

* Fixed infinite recursion in expression analyzer. [#CLICKHOUSE-3125]

* Update ActionBlocker.h

* Improvement [#CLICKHOUSE-2].

* Try fix strange terminate (#1329)

* Tests: External: rename --use_http  => --no_http and fix

* Try fix strange terminate

* Misc [#CLICKHOUSE-2].

*  Fix compile CallPointInPolygon on clang4 (Thanks to @vavrusa) (#1333)

* Fix compile with boost 1.65.1+ and clang 3.8 ( https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222439 )

* Fix compile CallPointInPolygon on clang4 (Thanks to @vavrusa)

* Fix complex queries with GLOBAL IN and UNION ALL  (#CLICKHOUSE-3356) (#1339)

* TEST only: why initQueryAnalyzer ?

* Better tests

* missing file

* Missing file

* Add test

* Test fixes

* Fixed FREEZE PARTITION: using only active data parts; acquire snapshot of parts [#CLICKHOUSE-3369].

* Removed tcp_ssl_port by default [#CLICKHOUSE-2].

* Better tests

* comment

* clean

* REmove wrong code

* clean

* dbms: Added compression level for ZSTD. [#METR-26742]

* dbms: CompressionSettingsSelector. [#METR-21516]

* dbms: Minor fix. [#METR-21516]

* Fix SummingMergeTree argument checking logic.

This patch fixes the Nested Column Name checking logic, which allows nested
columns be explicitly specified in SummingMergeTree engine.