save a few seconds by not running `apt-get update` every time
remove the html output from examples
remove references of cacheSweave, pgfSweave and highlight
update bib for knitr-manual.lyx
add a few section titles in the Rmd vignette
add a vignette.css; not polished, but at least the body width is not 100% now
mention all the vignettes in news
make news
bump version to 1.2; ready for CRAN now