created PidName and Evaluator (different one) modules

* Evaluator handles evaluating code, that means doing no
  message sending to Coordinator.
* PidName wraps the to_pid_name and is_pid_name?
* More stuff from Runner should be moved to Evaluator IMO.
# Please enter the commit message for your changes. Lines starting
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# On branch master
# Changes to be committed:
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#	modified:   lib/debugger.ex
#	new file:   lib/evaluator.ex
#	new file:   lib/pid.ex
#	modified:   lib/runner.ex
#
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#	evaluator.old.exs
#	lib/foo.exs