rework Hydrilla to use a separate tool for building its source packages...* Hydrilla now depends on "Hydrilla builder" developed at: https://git.koszko.org/hydrilla-builder/
* Hydrilla repository is now REUSE-compliant
* The debian packaging is temporarily not tested and likely to be broken
* JSON schemas are now in use (through 'jsonschema' Python library)
* This is not yet a release and some minor changes to the API on-fisk format are going to occur before that