a better solution for e.offsetX/Y in Firefox based on http://stackoverflow.com/q/12704686/559676

which fixes the bug reported by Greg D: https://groups.google.com/forum/#!topic/shiny-discuss/E6oYvyvx0oU
roxygenize
Fix typo
notify iframe parent of disconnect when on the same domain
Merge pull request #268 from rstudio/feature/parent-notify-disconnected

send disconnected message to parent frame when running on localhost
Merge pull request #265 from yihui/bug/offset

a more reliable solution for e.offsetX/Y in Firefox