check for null before manipulating style of name and description cells in environment
screen injected browser commands from history on server
fix debug stepping problems when debugger is invoked from R RPC calls
Merge pull request #51 from rstudio/bugs/debugging

Fix debug stepping problems when debugger is invoked from R RPC calls
Merge remote-tracking branch 'origin/master' into feature/environment-selector
hide internal environments; make display for unevaluated promises more accurate