Fixed fatal error

When copying the child theme path out of the mail `$file_paths` array and wrapping it in the `is_child_theme()` check, a comma was left. Just needs to be replaced with a `;`.
Correct method name

The `get_template_file_names` was renamed to `get_template_possible_parts` but then not updated in `get_template_part`. This fixes that.
Merge pull request #1 from pippinsplugins/develop

Fixed two fatal errors. One to be fixed in a different way imminently.