Failing: add a tiny Fq8 test field, to make test failures easier to diagnose

[teor2345]

This PR is blocked by bug #17. (It can't merge until that bug is fixed.)

This PR adds a tiny test field to make test failures easier to diagnose. It has parameters:

• q = 2ˆ8
• N = 4
• modulus = 239
• generator = 7

[teor2345]

Merging this even though it’s failing, so that the fix in #19 is in a separate commit to the rest of the changes.