Fix cursor positioning on Safari 6.1 and later

Adapted from http://github.com/ajaxorg/ace/pull/1566
Merge pull request #70 from rstudio/bugfix/safari-fractional-cursor

Fix cursor positioning on Safari 6.1 and later
qt colorspace patch
Merge branch 'master' of github.com:rstudio/rstudio
minimal change to prevent use of node-webkit on mavericks
don't use internal pdf viewer on osx (not compatible with mavericks; some issues on mountain lion)
ignore busy events when R isn't actually busy
Revert "osx: use qt 4.8.0 built from source if available"

This reverts commit 21891ebb0e4e87b0f93ccc39d5c6c61693697f40.
import osx dependencies
Remove node-webkit, causing build errors
Merge remote-tracking branch: upstream/master