Adding the pandoc-xnos filter

[Mahraz66]

Hi,
Nice pakage.
I am laso using xnos filters, so I just change the code a little:

`
case 'Latexmk + XeLaTeX':

    args.push('--pdf-engine=latexmk')
   args.push('--pdf-engine-opt=-pdfxe')
    args.push('--pdf-engine-opt=-output-directory=' + this.tempDir)
    args.push('--filter=pandoc-xnos')
    args.push('--citeproc')
    break

`
Maybe you can also add this option to this package

[allefeld]

Hi, I don't want to add many options to the package, because every user has their own preferences. I recommend to use the default file system instead. You can put a general or a writer-specific default file into the Pandoc directory, or a document-specific one into the current directory.