Improved performance of inserting into StorageDistributed with very high number of shards (not tested) [#CLICKHOUSE-2].

* Initial commit if EN docs

* Part of EN documentation

* Full queries section

* External data

* Table engines

* System tables

* Table functions

* Formats

* Data types

* Operators

* Functions

* Dictionaries

* Settings

* Configuration files

* Access rights

* Quotas

* Fixed few formatting errors

* Fixed few formatting errors

* Fixed few formatting errors

* FIX: "WARNING: Title underline too short." during build RU docs.

* FIX: "WARNING: Title underline too short." during build RU docs.

Add missing liblz4 header file

Move most AggregateFunctions to separate lib, use AggregateFunctionFactory as singletone, rename lib storages_system->clickhouse_storages_system

CastTypeBlockInputStream: hotfix: sometimes columns in sample blocks and stream blocks does not match

This implements a new function for approximate
computation of the most frequent entries using
Filtered Space Saving with a merge step adapted
from Parallel Space Saving paper.

It works better for cases where GROUP BY x
is impractical due to high cardinality of x,
such as top IP addresses or top search queries.

the last stable version 1.7.8 fixes build with
newer OpenSSL that’s in most of the distribution

* Add small .sh for easier report while investigating problem

* renamed:    clickhouse_report.sh -> report/clickhouse_report.sh

* fix new path

* Merge: fail if cant convert columns

* Merge: convert all different types, more tests

* clean

* clean

* clean