teem	/	unrrdu	unu swap

unu swap: Interchange scan-line ordering of two axes. Special case of
"unu permute".

Usage: unu swap -a <axisA axisB> [-i <nin>] [-o <nout>]

-a <axisA axisB> = the two axes to switch (0-based numbering) (2 ints)
        -i <nin> = input nrrd
       -o <nout> = output nrrd (string); default: "-"