comment.
style.
shared xcode schemes.
obj_is_valid_ref.
better env repr.
obj0 repr; simplified depth calculation.
int1 (unused).
Trace.elided_step_count.
comment.
remove VERBOSE_EVAL; add -t, -s options; add empty argument, unknown option checks.
RC_item now stores ref, not hash.
xcscheme arguments.
rc_dump, fix comment.
local variable for return value for debugging.
tail behavior altered to improve traces.