Requires runtime 14.142

Requires runtime 14.142

* Replace scheme-interaction mode by new inferior-repl mode.  The new
  mode runs a standard REP loop as an inferior coprocess, and supports
  both the runtime system's debugger and edwin's debugger.

* Transcript buffer used to be same as interaction buffer; now it is a
  separate buffer.  In addition, it records input expressions as well
  as the output.

* Extensive reorganization of debugger.  Only substantive change is
  for compatibility with changes to debugger in runtime system.
  However, the code is now organized in a somewhat top-down fashion,
  which should aid comprehension.

* Delete FRESH-LINE and FRESH-LINES procedures.  Former is supported
  in runtime system, latter is random.

* Editor cmdl changed to use new interface.