This changes showMixedAmountElided so that the width to elide to is
given as an argument, rather than fixed at 22 characters. This
actually uses the new renderTable interface. Mostly this is just an
internal change, but since we have more information about the widths
of things, we can actually get rid of some superfluous spaces in the
budget report output, previously there to make sure it stayed aligned
with the largest reasonable contents.
