[dev-context] fix for named destinations in URLs

Hi Hans, the attached patch replaces "#" with "^" as autoprefix for named destinations in lpdf.ano (both for MkXL and MkIV). This would allow urls such as https://pdf.ousia.tk/autoprefix.pdf#nameddest=^33 ("#" is a reserved char in urls). Also “PDF Open Parameters” reserves the usage of "#", "&", "=" and these special characters cannot be escaped (https://pdfobject.com/pdf/pdf_open_parameters_acro8.pdf#search=escape). I hope it helps, Pablo