Adds extra parameters to dt_create_missing_terms.

[mmcachran]

Description of the Change

Add taxonomy and term data to dt_create_missing_terms filter to allow whitelisting/blacklisting taxonomies/terms.

[jeffpaul]

Resolves #379

[jeffpaul]

@adamsilverstein @dkotter if either of you have time to review this that would be great, thanks!

[helen]

Leaving a review note: I just want to make sure that this doesn't impact existing hooked functions - there's a change in PHP 7 that can throw notices/errors if the number of args doesn't match but I don't remember off the top of my head what exactly causes the issue. If you do know, that'd be great, but otherwise I will look into this in the next week or two.

[adamsilverstein]

there's a change in PHP 7 that can throw notices/errors if the number of args doesn't match

@helen i couldn't find that change although i vaguely recall it. In any case, I think its only an issue if your function expects more parameters than are passed (and provides no defaults)? In that case, this change would be safe as its adding arguments so existing handlers would work as expected.

[helen]

Making suggestions so I can commit them :) Turns out the commit suggestions feature doesn't work for forks? Anyway, I committed them directly in Git.