This release has more small bug fixes and minor improvements:

* a backtrace now warns when it thinks the callstack is truncated which it gets by comparing with caller()

* fix setting $0.

* fix bug in showing variables in post-mortem

* Document how Debugger.start with a block is intended to be used.

* Move Kernel#debugger from ruby-debug-base into ruby-debug

* Get regression tests working again

* Warn and add a "confirmation" when setting a breakpoint on a file that is not loaded.