Submitted by: @fatalbanana

 - Use consistent naming for setup/teardown
 - Remove some unused files
 - Sort & align variables

 - Move neural functions to library
 - Parameterise spawn_train
 - neural plugin: Fix store_pool_only when autotrain is true
 - neural plugin: Use cache_set instead of mempool
 - Add test

 - Antivirus: better visibility into why test servers mightn't start
 - Antivirus: don't use ephemeral port range
 - Fuzzy skip hash: wait for map reload

 - Fix more deprecated Robot Framework syntax
 - Remove log following
 - Remove some artefacts in teardown
 - Restore use of demjson

Current ClickHouse version refuses to run from root if data directory is
not owned by root. Run it from user clickhouse as it supposed to be run.

Also cleanup ClickHouse config (some options prevented it to start,
others just unnecessary).

luacov-coveralls merge mode (-j flag) was created to join reports
containing coverage for different source files (e.g. C and Lua code).
Coverage for the same file in two report is not merged, instead one
source file is added several times to source_files array in JSON. As
a result if we use luacov-coveralls -j on report for same source files
it ends up spending a lot of time on parsing and dumping big JSON files.

This change reduces functional test time from 7+ minutes to 4+ minutes.

* reduce timeout to a reasonable value
* explicitly close socket, don't wait for GC

Currently functional test sometimes fails with and error:
Teardown failed: NoSuchProcess: psutil.NoSuchProcess process no longer exists (pid=2259)

Rewrite process termination - there is no need to send signals in a loop
many times.

Moved code for pid writing and terminating into a separated module.
Also added cleanup: in some cases, processes remained in the system after test is done. It should not happen anymore