Create a refactoring test suite with full code coverage

[axch]

Goal: Provide a safety net for refactoring.

Plan: Several extremely short-time and low-resolution runs, checking that the answers are identical bit-for-bit with a previous version. Can use the existing demo configurations as starting points.

Ideally:

• Cover all code paths.
• Execute as fast as possible. I mean that: 100 ms would be ideal.

To cover the stochastic wind feature, will need to control the initial random seed, which is a separate issue.

[axch]

Careful inspection (carried out while producing PR #19) suggests the following list of features not yet covered by the refactoring test suite introduced therein:

• [ ] Sponge region(s)
• [x] Non-empty depth file
• [x] Sinusoidal wind
• [x] Stochastic wind (blocked on Issue #8)
• [x] Non-empty meridionalWindFile
• [x] Non-zero initial U, V, and Eta
• [ ] Dumping wind files
• [x] Non-zero freesurfFac (blocked on Issue #16, I think)

[axch]

Unassigning myself, since constructing the additional examples needed to get full coverage is not something I am doing immediately.