no need to use srcfile when parsing chunk options
escape_regex() is not used by other functions, so not worth a separate function at the moment

also move stop() to the beginning for less indentation
write \author{} and \maketitle only if \title{} is not empty
add coffeescript to list of interpreted engines
factor out the common settings in Rnw, Rhtml and Rmd into stitch()
roxygenize
move stitch() from output.R to template.R
new functions stitch_rhtml() and stitch_rmd()
roxygenize
bump version
these options (fig, fig.low, fig.hold, animate, align, prefix.cache) only appeared in very early versions of knitr; perhaps nobody uses them now
a new function Sweave2knitr() to convert Sweave documents to knitr; closes #451
no longer fixes the inappropriate chunk options internally; users must Sweave2knitr() first if they are from Sweave
parse_params() is more light-weighted now; it no longer accepts Sweave syntax such as results=tex (#451)
parse_inline() no longer parses \SweaveInput{} and \SweaveOpts{} (#451)
call_inline() no longer sets global chunk options
reminder() is not useful anymore since it is for Sweave only
update test-parser.R since valid_opts() has gone
roxygenize
make inline.code and inline.comment arguments of parse_inline() so that it is easier to test and use this function