don't show checkboxes in environments where selection isn't meaningful
build the environment list popup menu dynamically on invocation
render column widths separately from columns (fixes layout issue in Mozilla)
fix problems with environment switching during debugging sessions
fix bug: error and output order is incorrect when they are interleaved
permit debugging inside functions defined at the console
gracefully handle case where environment being watched is unavailable after R restart
make debug stop button interrupt code if it's running
fix bug: after R is restarted, debugger state doesn't always get reset
show package-internal environments correctly in environment drop list (not yet viewable)
make package-internal environments selectable
show promise expressions in grid view as in list view
Merge pull request #60 from rstudio/bugs/debugging

Roundup of fixes for 0.98 bugs in debugger and environment grid view
Merge remote-tracking branch 'origin/master' into v0.98-shiny