5. Factor out the unit-norm basis (and operator symmetry) tests once
all of the algebras pass.
-6. Implement random_instance() for the main EJA class.
+6. Override inner_product(), _max_test_case_size(), et cetera in
+ DirectSumEJA.
-7. Implement random_instance() for the subalgebra class.
+7. Switch to QQ in *all* algebras for _charpoly_coefficients().