Fixed test case

Signed-off-by: K-ballo <k@fusionfenix.com>
Use `is_pass_through_unary` in attribute traits

Signed-off-by: K-ballo <k@fusionfenix.com>
Added handles_container trait

Signed-off-by: K-ballo <k@fusionfenix.com>
Enabled some tests in Jamfile

Signed-off-by: K-ballo <k@fusionfenix.com>
Defer default attribute trait implementations to avoid ambiguities

Signed-off-by: K-ballo <k@fusionfenix.com>