source instance acmag/acphase not reset to initial values when gnt analysis is finished

[jverbrug]

see test reference_simulation_1

when ac is run after gnt, wrong results when ac is run before gnt, correct results

[Bart Moeneclaey]

The initial values of the selected gnt source (or any source) are currently not available to the gnt analysis.

As such, after setting the source to 1 and 0 for various ac analyses required for the gnt analysis, the source cannot be reset to its initial value.

The current implementation is to set that source's acmag=1 after gnt analysis.

[jverbrug]

This should be fixed as it makes the gnt not transparent. I think only acmag and acphase of the source instance are required to pass to the engine.

[jverbrug]

although code in the python engine is present (refsim, norefsim), it is not yet called from SKILL