Function bookbinder_common::convert_pdf_to_svg

pub fn convert_pdf_to_svg(
    pdf: &[u8], 
    dpi: Option<usize>
) -> Result<String, Box<dyn Error>>

convert a pdf file to an svg; requires that pdftocairo (part of poppler) be installed. Note that we can't link poppler without licensing difficulties, so there are no plans to incorporate this as a dependency.