use cellspacing 1 (thin horizontal lines between code blocks)
move generator to the meta tag so it is not too intrusive
rely on grep instead of ==
a dark trick to make sure the pre blocks will end up in the same cell
largely rewrite docAdjust() so that if there are images output from the code blocks, they will be moved up (then the plots and code will sit side by side)

besides, the pilcrows are added to all the rows now
remove the default docco example
rename docco to docco-linear.Rmarkdown
rename the docco engine to docco_linear, and added a docco_classic engine for Rmkd files

in the future, I will renamed .Rmarkdown and .Rmkd to .Rmd; hopefully this problem can be solved in R 3.1.0
update examples for rocco()
plural; quiet knit()
roxygenize