capture.output() has already considered withVisible(), and we do not need to redo it
add a 'width' argument so we can control the width of the text output
a news item for the 'width' argument of renderPrint()
fixes #429, which is yet yet another WAT of RJSONIO

perhaps we really should consider switching to jsonlite...
\emph cannot be used in \code{}: only \var and \link are allowed
Merge remote-tracking branch 'origin/pr/485'

Conflicts:
	NEWS
add a 'width' option to selectizeInput() and sliderInput() to specify the width of these widgets
roxygenize
validateCssUnit(width) for selectize and slider
add width to selectInput() as well
examples of the 'width' argument
roxygenize
upgrade selectize.js to v0.9.1 to fix the third issue in #428
make sure the `selected` argument never contains names; fixes #428
fix #220: the first entry is not necessarily a directory

in that case, we use dirname() on the first entry
Merge pull request #488 from yihui/bugfix/220

fix #220: the first entry in zip is not necessarily a directory
Don't print NULL to the console during renderPrint
Avoid black background when renderPlot doesn't actually plot
Validation error causes real errors to look like validation errors

The CSS class for validation errors was not being properly removed between different kinds of errors
Suppress validation errors from printing at console