* continuations.c, debug.[ch], eval.c, gscm.c init.c, root.c,

* continuations.c, debug.[ch], eval.c, gscm.c init.c, root.c,
throw.c: Renamed last_debug_info_frame -> scm_last_debug_frame.

* throw.c: Renamed scm_catch --> scm_catch_apply and added more
arguments.  The motivation is that code in root.c needs catch
functionality, and we want to avoid code duplication.
New functions: scm_catch, scm_lazy_catch.  These are wrappers for
scm_catch_apply.  scm_lazy_catch is intended to introduce catch
handlers that run without popping the stack into the dynwind
chain.