use a different default splitter location for the left pane
fix bug: debug(exists) can result in infinite recursion
fix bug: reported exception in getDisplayValue() (guarantee value and description are not null)
ensure that openProjectDocs works correctly (call openFile using continuation, eliminate possibility of phantom document)
Merge branch 'master' of github.com:rstudio/rstudio
add stub for viewer tab
initial implementation of browser.internal via viewer
Merge remote-tracking branch: upstream/master