fix source comparison problems for functions in package environments and display of langauge objects
allow for richer (html) error reporting from presentation rendering
eliminate error response action field
playback knitr errors into presentation slide
simplify presentation error response struct
extract r error message from knitr stderr
Merge pull request #30 from rstudio/feature/callstack

fix source comparison problems for functions in package environments
command to clear the knitr cache for the active presentation
add contextual toolbar to the console for debug commands (continue, stop, step)
install overlay before common dependencies on the mac
Merge pull request #31 from rstudio/feature/debug-toolbar

add contextual toolbar to the console for debug commands (continue, stop, step)