change to TAB as separator for frequency analysis (-q) fields

[roycewilliams]

Today, -q output is separated/padded by spaces. Because spaces are often present in raw founds, this can make automated post-processing harder.

If a single TAB was used as the separator instead, then tools like cut, awk, etc could work more precisely with the output of -q.

(Specifying -q separator could be an option flag, but IMO I think it would be cleaner to just change to using TAB wholesale.)

As a related change probably not worth an extra issue, eliminating the right-justification of the first column would eliminate some tedious post-processing, and bring the output in alignment with other frequency-count tools' output.