initial support for no-srcref debugging
correct line highlighting for deparsed calls
always show the top function on the stack
initial support for no-srcref debug stepping
support for stepping over multi-line statements
don't reset code browser state on every debug step
handle stepping through functions with identical statements
improve source viewer tab behavior
avoid reconstructing references that match entire function body
show bar warning that location is approximate
fix inaccurate refs when first step is over a dupe
Merge remote-tracking branch 'origin/master' into feature/no-srcref-debugging
improve reference handling for line debug state
allow user to explore non-srcref code after debugging begins
Merge pull request #87 from rstudio/feature/no-srcref-debugging

Support for debugging without source references