if we set the chunk option dev.args = list(useDingbats = FALSE), it may be passed to other devices such as png; see comments under 1029bd9

knitr 1.5.31 makes it possible to set device arguments for a single device using a named list
reduce height of iframes in ioslides
Merge branch 'master' of github.com:rstudio/rmarkdown
bump version
tweak iframe sizing in ioslides
only run pandoc-citeproc if a bibliography field is specified
Change pre_processor to take input_file; preserve marked HTML

- Preserves any HTML regions marked with <!--html_preserve-->...<!--/html_preserve-->
- In order to make this feature possible, I had to modify pre_processor to take input_file, not input_lines
Merge pull request #65 from rstudio/feature/shiny-dependencies-html-preserve

Change pre_processor to take input_file; preserve marked HTML
cleanup from pre_processor refactor
URL-decode path information in Shiny Run Document case
emit relative rather than OS-specific path in HTML (when not self-contained)
Merge remote-tracking branch 'origin/master' into feature/shiny-dependencies
run: treat filename provided as relative to directory provided
Check for critical environment variables.

Ensure that LANG and HOME are both set before running Pandoc, as their
absence can cause fatal errors as discussed in #31.
Merge branch 'master' into feature/shiny-dependencies