Fatal error: Call to undefined function bindtextdomain() in [...]

This error might be caused by a missing GetText extension. If this is the case, you have to enable the extension in your php.ini:

extension=php_gettext.dll

If the extension is not installed yet, this is how to install gettext on macOS (for PHP7.0):

sudo port install php70-gettext

Afterwards, do not forget to restart Apache:

sudo port unload apache2
sudo port load apache2