* #2249 allow macros while creating kafka engine

* Update Macros.cpp

* Update Macros.h

* Add system table: merge_tree_settings

* Some improvements for introduction/performance.md

* Minor improvements for example_datasets

* Add website/package-lock.json to .gitignore

* YT paragraph was badly outdated and there is no real reason to write a new one

* Use weird introduction article as a starting point for F.A.Q.

* Some refactoring of first half of ya_metrika_task.md

* minor

* Weird docs footer bugfix

* Forgotten redirect

* h/v scrollbars same size in docs

* CLICKHOUSE-3831: introduce security changelog

* A bit more narrow tables on docs front page

* fix flag in ru docs

* Save some space in top level of docs ToC

* Capitalize most words in titles of docs/en/

* more docs scrollbar fixes

* fix incorrect merge

* fix link

* fix switching languages in single page docs mode

* Update mkdocs & mkdocs-material + unminify javascript

* cherrypick https://github.com/olivernn/lunr.js/commit/17e18d1ecc8a0b44e08cd088c979acd2598d80da

Mark library headers as system (this is intended to enable more warnings in application code) [#CLICKHOUSE-2]

Mark Poco headers as system (this is intended to enable more warnings in application code) [#CLICKHOUSE-2]

* add setting prefer_localhost_replica

* add prefer_localhost_replica setting

* fix bugs

* update setting comment

* Add test for prefer_localhost_replica

* fix bug

* Format ODBCDriver2 with NULL support

* Fix comment

* Update ODBCDriver2BlockOutputStream.cpp

* clean

Better CMakeLists for rdkafka library.

This reverts commit 2f2fafb7.

Add new error check for fetchPartition operation