vasevid and fillval are applied

have a fillval attribute, allowing column-specific fill value to be set - used
by binariseCategorical.

column data gets formatted correctly

have a "basevid" attribute, for columns which have been derived from other
variables

kwargs, rather than just acceptiong a list of metadata

present in the data set

Enh/binarise different values

See merge request !37

Broadcast arguments are *not* supported for processes which are applied
simultaneously to a group of variables - the logic to do this would have to be
baked into the process function itself.

plugin decorator "auxvids" argument.

serially (it has always been used like so, so doesn't need any logic to
perform both in one invocation). Passes broadcast indices to process.run when
specified

function. Tempdir/logging is managed by processData (will be removed from
runProcess).

set to a list of values, and its name prefixed with "broadcast_"; an
index into the list can then be specified on calls to run(), and the
corresponding value passed to the process function.

of columns, instead of generating binary columns. Avoid deprecation warning
in loadtables.

Bf/import all column

See merge request !35

calculation