New features

• ISAICP-4495: Provide a demo environment that allows to test upcoming features over a longer time period.

Bugfixes

• ISAICP-4499: The predicate for the "Owner type" was not adhering to ADMS specifications.
• ISAICP-4500: Predicates for the "Solution type" and "Test resource type" fields were not adhering to ADMS specifications.
• ISAICP-4521: An exception was thrown when editing policy domain terms.
• ISAICP-4523: The predicates for the "Spatial coverage" field in collections and solutions were not adhering to ADMS specifications.
• ISAICP-4524: The predicates for the "Documentation" field in collections and solutions were not adhering to ADMS specifications.
• ISAICP-4525: The predicates for the "Release notes" field in collections and solutions were not adhering to ADMS specifications.
• ISAICP-4527: The predicate for the "Representation technique" field in distributions was not adhering to ADMS specifications.
• ISAICP-4282: Only send 1 notification to the author of a discussion when the discussion is being deleted.

Improvements

• ISAICP-4392: Update button labels to avoid confusion between cancelling an account, or cancelling the cancelling of an account.
• ISAICP-4514: Update to PHPUnit 6.