debian: add dependency on zstd

Merge pull request ClickHouse#440 from ClickHouse/bump-to-2.6.0

Bump version

debian: add depencdency on libabsl-dev to development package

debian: add Debian packaging files

Merge pull request ClickHouse#336 from Enmk/fix_issue_335_no_connecti…

…on_attempts

Fixed issue ClickHouse#335 by making at least one connection attempt

Merge pull request ClickHouse#333 from Enmk/set-backward_compatibilit…

…y_lowcardinality_as_wrapped_column-deafult_value_to_false

Set backward_compatibility_lowcardinality_as_wrapped_column default value to false

Merge pull request ClickHouse#300 from Enmk/deprecate_LowCardinalityS…

…erializationAdaptor

Minor: Deprecated LowCardinalitySerializationAdaptor

Merge pull request ClickHouse#249 from 1261385937/performance_improve

ColumnString improve performance(26%) by avoiding vector reallocate

Update README.md

Update LICENSE