support output format composure (for isolating dependency injection)
factor common HTML output formats into html_document_base
allow injection of custom dependency resolver
update documentation and pandoc_args
doc changes; sync with shiny::attach_dependency
validate dependencies in HTML dependency resolver
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
Merge remote-tracking branch 'origin/master' into feature/shiny-dependencies
run: treat filename provided as relative to directory provided
merge_scalar for combining post_processor
Update DESCRIPTION
don't use non-exported attach_dependency from shiny
order base and overlay output format post-processors
Merge pull request #74 from rstudio/feature/shiny-dependencies

Shiny dependency handling