_license/README.TXT: clarified that this folder contains authority information proving the open-source status of parts of the codebase. added recommendation to include this folder when redistributing, so that the open-source proof is included along with the license text.

_license/LICENSE.TXT: renamed to README.TXT because this actually contains a description of the folder, not license text

schemas/Makefile: removed no longer used rename/%, rotate. use %/install, %/publish instead to manage public schema versions.

schemas/Makefile: removed no longer needed public/uninstall, which is handled more generally by `%/uninstall: vegbien.sql` instead

schemas/Makefile: `%/uninstall: vegbien.sql`: added support for *_validation schema

schemas/Makefile: %/uninstall: split into 2 rules like for %/install, so that different actions can easily be added for the public schema

schemas/Makefile: %/publish: support auxiliary *_validation schemas

bugfix: schemas/Makefile: `%/install: vegbien.sql`: need -e before each s/// expression

schemas/Makefile: `%/install: vegbien.sql`: create a custom _validation schema for *each public schema, rather than one for the most recently-created public schema. this allows validations to continue to be run against a previous version of the DB while a new version is being imported.

validation/aggregating/traits/bien3_validations_traits_bien3.sql: include only records from the bien2_traits datasource, to ensure that the scope of all queries is limited to the datasource