Fix writing indexed PNG palettes
Fix writing indexed PNG palettes

ixiom/pdfkit,moyogo/pdfkit,ashelley/pdfkit,devongovett/pdfkit,jkol/pdfkit,joadr/pdfkit,moyogo/pdfkit,gabrieldelatorreicg/pdfkit,datphan/pdfkit,jordonbiondo/pdfkit,gabrieldelatorreicg/pdfkit,billcowan/pdfkit,mauricionr/pdfkit,ixiom/pdfkit,gradecam/pdfkit,mauricionr/pdfkit,datphan/pdfkit,joadr/pdfkit,billcowan/pdfkit,jkol/pdfkit,greyhwndz/pdfkit,pomahtuk/pdfkit,backspace/pdfkit,aendrew/pdfkit,devongovett/pdfkit,jordonbiondo/pdfkit,gradecam/pdfkit,greyhwndz/pdfkit,bpampuch/pdfkit,pomahtuk/pdfkit