* expprint.c (print_subexp): Add OP_NAME support.
* parse.c (length_of_subexp, prefixify_subexp): Likewise.
* scm-lang.c (scm_unpack, in_eval_c, scm_lookup_name): new function.
* scm-lang.h: Declare builtin_type_scm; other minor tweaks.
* values.c (unpack_long): If type is SCM, call scm_unpack.
* scm-valprint.c (scm_val_print): Use extract_signed_integer,
instead unpack_long
* scm-lang.c: More Scheme expression parsing from here ...
* scm-exp.c: ... to here. New file.
Also, provide for gdb to evaluate simple constants and names..
* Makefile.in: Note new scm-exp.{c,o}.
