Add absolutePanel and fixedPanel (and jquery-ui)

jQueryUI is needed for draggable functionality.
Smarter cursor choosing for absolutePanel
Minor doc tweak
Merge remote-tracking branch 'origin/master' into feature/absolute-panel

Conflicts:
	DESCRIPTION
Unify jqueryui copies
Remove caTools dependency
allow display.mode to be provided for examples
Merge pull request #298 from jcheng5/remove-catools

Remove caTools dependency
Merge pull request #388 from rstudio/feature/example-display-mode

Allow display.mode to be provided for examples
closes #25: a new function includeMathJax()
a news item for includeMathjax()
Merge pull request #364 from yihui/feature/mathjax

closes #25: a new function includeMathJax()
Merge remote-tracking branch 'jcheng5/feature/absolute-panel'

Conflicts:
	NEWS
	man/validateCssUnit.Rd
Add index entry for absolutePanel
tweak news
strip white spaces
use @include to make sure the Collate field is correctly generated
using roxygen2 4.0.0: the spurious changes are due to klutometis/roxygen#184 (text in Rd is no longer wrapped by default)
use Rd2roxygen to convert the two manually written Rd files to roxygen comments, so that all Rd files are automatically generated from roxygen2 now
ignore staticdocs/ when building the source package