~/.mailcap: handle pdfs with evince.

xdg-open seems unreliable, various apps install their own handlers. is
there a reliable way to configure xdg-open with a text file?

.mailcap

text/html; pandoc -f html -t markdown_strict %s; copiousoutput;
application/pdf; xdg-open %s; copiousoutput;
application/x-pdf; evince %s; copiousoutput;
application/pdf; evince %s; copiousoutput;
application/rar; lsar %s; copiousoutput;