The compare() function now saves a shallow copy of
the input tables. This means functions using a comparison,
e.g. slice_diffs(), now only need the
comparison argument, rather than requiring the original
input tables to be re-supplied.
New functions weave_diffs_wide() an
weave_diffs_long() are added, which show the differing
values in context with other columns from the input tables.
A new function slice_unmatched() is added, used to
get the rows from input tables a comparison shows as not existing in the
other table
A new function slice_diffs_both() is added, used to
get the differences from both input tables in a single output with the
rows interleaved
The error message for duplicated by values now shows
the row which is duplicated
Comparisons are now faster