When invoked without argument or with interactive a dialog box
is presented, allowing the user to do the same operations as with the
action.
If the first argument select, further OpenEMS exports will use
the excitation named in the excitationname argument (in short:
the excitation is selected).
Arguments set and get is used to read or change an
excitation parameter named in paramname. When excitationname
is not set, they operate on the currently selected excitation. For set
the paramval argument is mandatory.
Note: the code remembers all settings for all excitements, not only the
excitement that is currently selected. The selection and all parameters are
saved as board attributes.