Sync get_the_category_list with get_the_term_list

[markoheijnen]

It would be great to have get_the_term_list() support the same features get_the_category_list() has.

I created a proof of concept patch what works. The only thing I hate is the part I need to specify that I want to have a list instead of a separator because when it's empty get_the_category_list() assumes to show a list but get_the_term_list() will then just show only the links.

[boonebgorges]

This would be pretty great. I'd feel more comfortable with it if either of these functions had any unit test coverage.

Moving the call to get_category_parents() into get_the_term_list() is problematic, because get_category_parents() is compatible only with categories. This would probably have to be accompanied by a taxonomy-agnostic get_term_parents() (with get_category_parents() converted to a wrapper).

[markoheijnen]

I totally missed get_category_parents. I will work on the improvements this week and then also add unit tests.