+7. Figure out if CombinatorialFreeModule's use of IndexedGenerators
+ can be used to replace the matrix_basis().
+
+8. Move the "field" argument to a keyword after basis, jp, and ip.
+
+9. Add back the check_field=False and check_axioms=False parameters
+ for the EJAs we've constructed ourselves. We can probably pass
+ the value of "check_axioms" to <whatever>.span_of_basis() to skip
+ the linear-independence check.