dgroup/vcs4sql

# @todo #/DEV Enable Travis CI as second CI server once the project
#  became a public. This might be alternative for Circle CI (just in case)

# @todo #/DEV Explain in readme.md how to use the project,
#  add more instructions and generic guide.

# @todo #/DEV There a lot of badges in readme which aren't enabled for now.
#  Let's enable them.

# @todo #/DEV Publish a gem to the rubygems.org. Add this instructions to the @Rultor.
#  No manual actions required.

# @todo #/DEV Migrate to ruby 2.7.0. For now the project has 2.6.5.
#  The project is new, it shouldn't be so expensive.

# @todo #/DEV Think about support of Postgres, MySQL, Oracle and others.
#  We need to reuse the existing structure as much as we can.
#  Most of classes which are oriented on SQLite should be modified.
#  The structure of potential upgrade folder might be the following
#  ...
#  |- lib
#  |- test
#  |- upgrade
#  ||||- sqlite
#  ||||||||- 00-define-initial-structure.sql
#  ||||||||- 02-add-missing-foreign-keys.sql
#  ||||||||- 03-add-missing-indexes.sql
#  ||||||||- 99-add.testdata.sql
#  ||||- postgres
#  ||||||||- ...
#  |||||- mysql
#  ||||||||- ...
#  |- Gemfile
#  ...