Render a Markdown file with natbib bibliography
the name of the Rmd file.
the path of the Rmd file.
the encoding of the Rmd file. Default to 'UTF-8'.
the LaTeX engine the compile the document.
Defaults to "xelatex".
open the pdf in a reader. Defaults to TRUE.
keep intermediate files after successful compilation. Defaults to "none".
TRUE to clean intermediate files created during rendering of the
R markdown into tex.
Other utils: 
add_author(),
add_report_numbers(),
check_dependencies(),
column_start(),
column_width(),
cover_info(),
create_report(),
dyn_table(),
references(),
validate_doi()