If the property name matches the foreign key name
creating a BelongsTo relation triggers an undefined
property error. Disabling constraints prevents
accessing the property and thus prevents the error.
* tests: be more systematic when testing discrete column types
Still not covering all due to SQLite limitation
* tests: relations of models
* tests: model in another namespace gets correctly qualified
* tests: cover SoftDeletes trait
* tests: cover some variants of getter