The recent update is mainly just code changes behind the scenes.
Just a note for any of you with custom certificate types.
The function cert_printtext is now named certificate_print_text, draw_frame is now named certificate_draw_frame, draw_frame_letter is named certificate_draw_frame_letter, so these will need to be changed. The functions to print the images (eg. print_watermark, print_seal etc) have been changed to use one function certificate_print_image that takes a parameter specifying what the image is.
certificate_print_image($pdf, $certificate, CERT_IMAGE_BORDER, $brdrx, $brdry, $brdrw, $brdrh);
certificate_print_image($pdf, $certificate, CERT_IMAGE_WATERMARK, $wmarkx, $wmarky, $wmarkw, $wmarkh);
certificate_print_image($pdf, $certificate, CERT_IMAGE_SEAL, $sealx, $sealy, '', '');
certificate_print_image($pdf, $certificate, CERT_IMAGE_SIGNATURE, $sigx, $sigy, '', '');