DKES Integration

[lazersos]

The DKES code as written was designed to allow the user to run with multiple E-filed/collisionality pairs but that functionality has been removed over time. What should really be done, is to restructure the code allowing for two improvements:

1. The code should be restructured so that an array of surfaces, e-field, and collisionality sets can be calculated. This is not trivial as each surface probably needs a separate call to dkes_input_prepare.
2. The loop over the sets of calculations should be parallelized. This also implies that calculation of a specific set (s,E,nu) should be handled by a single call.

This could take some time to implement and would direclty touch the interfaces to STELLOPT and THRIFT.