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.
Previously -B implied -x; now any of the valuation flags do.
This avoids a bug where print -V of a transaction with an implicit
commodity conversion would convert only some of its postings to value.
Also, more valuation tests.
-V (and -X) now respects a report end date set with -e/-p/date: when
choosing the valuation date, similar to hledger 1.14 and Ledger.
This means that -V/-X aren't exactly like either --value=end or
--value=now. The "Effect of --value on reports" doc has been extended
accordingly, and much of it has been reworded and made more accurate.
