Use numba to speed up calc_correction_per_corrprod
Use numba to speed up calc_correction_per_corrprod

The original code produced a Fortran-order array, which caused the apply
functions to be very slow. Just doing a separate transposition was also
quite slow - it's necessary to get things transposed before expanding
from inputs to baselines, and numpy fancy indexing seems to turn things
back into Fortran-order.

ska-sa/katdal