new version of SIOD, Scheme in One Defun

[gjc@bu-it.bu.edu]

Version 1.5 of SIOD is now available via anonymous ftp to bu-it.bu.edu,
CD to "src/gjc" and get "siod-v1.5-shar".

New features:
 * modularized with small main program in one file, scheme runtime
   and REPL in another.
 * stop-and-copy or mark-and-sweep GC selectable via command line argument,
   -g0 for mark-and-sweek, -g1 for stop-and-copy.
 * On 3 architectures tested, VAX, SUN3, ENCORE, the code in -g0 mode
   to mark the stack and registers is effective. Therefore GC can happen
   at any time during EVAL, READ, etc.

-gjc