Merge pull request #616 from knokknok/master

removes redundant information in dep_list
add a prefix argument to write_bib(), per suggestion of Michael Friendly
John Fox is using Authors@R now; smart! Michael added several other tweak items
roxygenize and bump version
a better way to suppress the progress bar
no need to try(); shiny will do it by default
cosmetic
factor out get_dargs() to filter out device args
factor out pdf_null()
pass dev.args to the pdf recording device if possible
bump version