closes #439: use Imgur API v3
tweak doc of imgur_upload()
roxygenize
changed mind on #395: use the global option instead of environment variable R_KNITR_PROGRESS for package option `progress`
allow users to set the width option via KNITR_WIDTH instead of hard-coding it to 75L
cosmetic
need both the svn rev number and R version to check tools::vignetteEngine
another svn mirror
if dir is null, do not set/reset working dir
run 'after' hooks in the base.dir if set (this will affect hook_rgl, hook_pdfcrop, ...)
add base.url to the mp4 video
add encoding support to knit2wp(): http://yihui.name/knitr/demo/wordpress/#comment-796562951
do not need to calculate file_ext() twice
bump version; should be ready to release v1.1