[meom code clinic] add more unitary test and another test case

[rivera-ma]

• There is one test case "gaussian eddy" is it possible to add another one?
• Some Unit test on simple functions could be implemented.

[vadmbertr]

• the gaussian scenerio is the only one where we have an analytical solution to the cyclogeostrophic balance, so it will be hard to find another "end-test" case I think.
• definetely (but it requires time!)