Delivery of new features and bugfixes into master branch.

Optimization of update_posts_rshares procedure (created dedicated temporary index to force Index Only Scan during query execution.

mentioned in merge request !517 (closed)

1. Installation improvements:
   1. Explicitly set versions of dependencies
   2. Eliminated use of git-commit references packages (what required newest version of pip tool and lead to fail when default one on Ubuntu has been used)
2. Fixes:
   1. Improved custom_json_operation processing order (to match their original order in blockchain), what previously could lead to operation failure in specific cases
   2. Adjusted collected votes rshares to the rshares split already done at HF6. Insignificant for current votes, but improves accuracy of old data (required for internal regression testing)
   3. Bugfixes in the Community related APIs i.e:
      • bridge.list_community_roles
      • bridge_api.list_subscribers
   4. Changes done in the database at LIVE sync are made at one-transaction basis for sanity. Also database stores information about clean state of data specific to given block.
3. Features:
   1. Preliminary support for synchronization from SQL based operation data source (prerequisites to redesigning Hivemind as HAF based application)
   2. Tweaks to enable support for an automated Code-QL analysis
   3. Improvements to SIGINT handling
   4. [DEBUG] Ability to log postgres vacuum analyze output on dedicated queries
4. Optimizations:
   1. Collected votes are removed when given post is deleted (reduces storage and improves data accuracy).
   2. Simplified cashout processing for unpaid posts (eliminate update of posts data which can change soon in next blocks)
   3. Reduced memory usage of python process executing hive sync code
   4. Speedup of update_posts_rshares procedure execution
   5. Eliminated posts active flag propagation as not used by API clients
   6. Tweaks to After Initial Sync phase to eliminate database storage increase (reordered execution of some actions, to free space before generating another part of data, use of TRUNCATE statement to allow Postgres to immediately reuse database space)
5. Organisational changes:
   1. All API regression tests moved directly into hivemind repository

merged

mentioned in commit e8cf0ff9

mentioned in commit d73bd507