Fixes every user-facing defect in 2.1.0's flagship command.

dkx wout_*.nc rendered three empty panels: the monoenergetic scan alone cannot
fill them, so the run now also solves for the geometry and scans the radius.
The bootstrap current is a radial profile with the ambipolar Er beside it,
evaluated AT that root rather than at Er=0; the flux panel is a radial profile
with the species named rather than a bar chart indexed by number.

Adding --out crashed the command outright.  The monoenergetic grid spanned two
decades and hid the 1/nu branch; it now runs 1e-4 to 1e2.  |B| was drawn in
index units with zeta over a full turn instead of one field period.  A run now
always writes an output file beside the figure.

Handing a VMEC wout to the namelist reader produced an opaque
UnicodeDecodeError; binary files are named, with the fix suggested.