Hydrilla

this commit is a backup of a part of bigger unfinished work and will be force-pushed over later

use pyproject.toml for pytest configuration and move all tests to tests/ directory

properly raise error when REUSE is needed but not installed

add support for --version option

don't include schema patch version number in generated instances

update schema versions to 1.0.1

fix "no translation file found for domain" error

change translation domain to 'hydrilla-messages'

enable using with Python 3.7

make "uuid" an optional property