Psydac MHD operators: new unittest
- Return non-flattened DOFs in tested MHD operators.
- Return right-hand side in "dot" method of psydac MHD operators.
- Use new Mhd_ops class for testing psydac MHD operators
- Remove random test vectors, use np.arrange instead
- Add operator Y20 to tests
- works now in parallel for powers of 2
- Added psydac mhd operators to unit tests.
- Remove some packages from install, require sympy version.
- Added assemble methods for each MHD operator to MHD_ops class.