Log Message:
Update to 1.13

Upstream changes:

CHANGES IN knitr VERSION 1.13

NEW FEATURES

    code chunks that generate metadata may be cached now; it requires \ 
htmlwidgets >= v0.6 and htmltools >= 0.3.3 if you cache code chunks that \ 
contain HTML widgets or Shiny inputs/outputs (#1158)

    when the output format is not HTML, HTML widgets used to fail to render; now \ 
knitr will try to generate static screenshots for HTML widgets automatically \ 
using the webshot package; you can specify alternative screenshots via the chunk \ 
option screenshot.alt (which takes a character vector of image paths), and pass \ 
more options to webshot::webshot() via the chunk option screenshot.opts, e.g. \ 
list(delay = 3, cliprect = 'viewport')

    added two functions include_url() and include_app() to embed URLs in the \ 
output (the latter is for Shiny app URLs); when the output format is HTML, \ 
iframe will be used; otherwise screenshots of the URLs will be used

    screenshotting for HTML widgets and URLs can be forced for all output \ 
formats via the chunk option screenshot.force = TRUE; if you set the chunk \ 
option screenshot.force = FALSE, knitr will just render these content normally \ 
and not take screenshots

    added a new chunk option fig.link, which can be used to attach hyperlinks on \ 
figures, e.g. you can add a link to a screenshot of a Shiny app so that readers \ 
can check out the actual live app after clicking on the static screenshot (this \ 
chunk option currently only works for Markdown and LaTeX output)

    syntactical errors in code chunks will be allowed when the chunk option \ 
error = TRUE and the package version of evaluate is at least 0.8.4; previously \ 
knitr would just stop on parsing errors (hadley/evaluate#65)

    PNG/JPEG images included via include_graphics() also respects the chunk \ 
option dpi now; if it is numeric and the chunk option out.width is not set, the \ 
output width (in inches) of an image will be automatically calculated from the \ 
actual width (in pixels) divided by dpi; note this feature requires the packages \ 
png and/or jpeg to be installed, and you can disable the feature using dpi = NA \ 
(thanks, @hadley, rstudio/bookdown#38)

    added a new hook function named evaluate in knit_hooks so that users can \ 
redefine a evaluator to evaluate the code chunk; the default is \ 
evaluate::evaluate(), and your custom evaluator must be compatible with \ 
evaluate::evaluate() in terms of the argument names and the data structure of \ 
the returned value (a list of values with special classes)

    added a new function combine_words() to combine multiple words / phrases \ 
into a single string, which may be useful in inline R expressions, e.g. \ 
combine_words(c('a', 'b', 'c')) returns a, b, and c

    render_markdown() gained a new argument fence_char to customize the \ 
character to be used as the code blocks fence, e.g. it can be a backtick, or a \ 
tilde, depending on the Markdown rendering engine (thanks, @tinyheero, #1161)

    the pandoc() function no longer assumes Markdown input (thanks, @scls19fr, #1170)

    added a new function knit_meta_add() so that users can manually inject \ 
metadata into the current knitr session

    for the tikz engine, if fig.ext = 'svg', dvisvgm will be called to convert \ 
the DVI output of TikZ to SVG; you need to install dvisvgm, and Windows users \ 
have to install GhostScript as well (thanks, @dkilfoyle, #1177)

    new js and css engines which surround their content with <script> and \ 
<style> tags respecitvely, and print no output when not in an HTML \ 
document

    for LaTeX tables, kable() supports short captions now via the caption.short \ 
argument, e.g. kable(..., caption = 'A long caption', caption.short = 'A short \ 
caption') (thanks, @ismayc, #1199)

    added three global R options knitr.sanitize.errors, knitr.sanitize.warnings, \ 
and knitr.sanitize.messages to mask or change the messages, e.g. if \ 
options(knitr.sanitize.errors = TRUE) and the chunk option error = TRUE, the \ 
actual error message will be replaced by a character string like "An error \ 
occurred"; these options can also accept character values so you can \ 
customize the messages to be displayed, e.g. options(knitr.sanitize.warnings = \ 
'You had a warning from the code'); see rstudio/shiny#1123 for the motivation of \ 
these options

BUG FIXES

    when the chunk option cache.rebuild = TRUE, the cache database should be \ 
rewritten (thanks, Oleg Mayba)

    include_graphics() did not work in inline R expressions (thanks, @WastlM, #1166)

    the cex parameter was not correctly restored in the case of \ 
opts_knit$set(global.par = TRUE) (http://stackoverflow.com/q/35606445/559676)

    for Rnw documents, when there are two instances of \documentclass{}, knitr \ 
might mistakenly treats the second instance as the the actual command to declare \ 
the document class (thanks, #1180, @ekstroem)

    corrected the environment for evaluating R scripts in stitch_rhtml() and \ 
stitch_rmd() (thanks, @Hughan, #1207)

MAJOR CHANGES

    the default value of the package option eval.after is changed from NULL to \ 
fig.cap, i.e. the figure caption will always be evaluated after a code chunk is \ 
evaluated (thanks, @JoshOBrien, #1165)

    the function eclipse_theme() has been removed since the website \ 
eclipsecolorthemes.org has been down for a long time