* Added PMPRORH_DIR constant. Now using constant to enqueue stylesheets.
* Will now look in /themes/{YOUR THEME}/paid-memberships-pro/register-helper/css/ for copies of the CSS files, which will be used in place of the default CSS files if found.
* Fixed required field error so it will not show duplicate warnings for fields with the same name and will use proper grammar when 1 field is missing.