write r code in two lines
add diagram to dependencies
\textcolor was changed to \color (yihui/knitr#432)
an example of moving code to appendix
chunks in html have id's now (chunk label)
break the long line to fit in the book
highlight=TRUE for Rmd now, so cache was broken (yihui/knitr#447)
rm *.toc for make clean too
an example of the Example environment based on amsthm
knit_expand(): a better template example than examples 020 and 041 (yihui/knitr#397)