Alessandro Arzilli authored Jan 10, 2017 and Derek Parker committed Jan 09, 2017

* service: Prevent panics from crashing delve and killing the target

Catch all unrecovered proc and debugger panics in the service layer and
report them as errors, allow users to cleanly detach from the target
and quit.

Fixes #614

* proc: Next/Step should not panic if line info can not be found.

Fixes #683