Passing ids to .select API seems to make partial string matches

[nbdavies]

If you're columns are named things like "animals" and "non-animals", then you may run into problems when you call:

graph.select('non-animals')

This will select the 'animals' data points as well.

It seems arbitrarily limiting to require that column names not contain one another.

[nbdavies]

It occurs to me that wrapping the single id in an array probably avoids the issue:

graph.select(['non-animals'])

In c3_chart_fn.select found within api.selection.js, indexOf is expected to be doing array matching, but could accidentally be doing string matching as well:

isTargetId = config.data_selection_grouped || !ids || ids.indexOf(id) >= 0,

Same applies for unselect().