First version of new shell process structure
First version of new shell process structure

This structure is based on the standard erlang shell. It has a
separate evaluator process and can handle that process crashing. It
does not yet save the process dictionary of the evaluator.

rvirding/lfe,jjhoo/lfe,jjhoo/lfe,rvirding/lfe,lfe/lfe,lfe/lfe