Add parameter support for Guile.

Add parameter support for Guile.

	* Makefile.in (SUBDIR_GUILE_OBS): Add scm-param.o.
	(SUBDIR_GUILE_SRCS): Add scm-param.c.
	(scm-param.o): New rule.
	* guile/guile-internal.h (gdbscm_gc_dup_argv): Declare.
	(gdbscm_misc_error): Declare.
	(gdbscm_canonicalize_command_name): Declare.
	(gdbscm_scm_to_host_string): Declare.
	(gdbscm_scm_from_host_string): Declare.
	(gdbscm_initialize_parameters): Declare.
	* guile/guile.c (initialize_gdb_module): Call
	gdbscm_initialize_parameters.
	* guile/lib/gdb.scm: Export parameter symbols.
	* guile/scm-cmd.c (gdbscm_canonicalize_command_name): Renamed from
	cmdscm_canonicalize_name and made public.  All callers updated.
	* guile/scm-exception.c (gdbscm_misc_error): New function.
	* guile/scm-param.c: New file.
	* guile/scm-string.c (gdbscm_scm_to_string): Add comments.
	(gdbscm_scm_to_host_string): New function.
	(gdbscm_scm_from_host_string): New function.
	* scm-utils.c (gdbscm_gc_dup_argv): New function.

	testsuite/
	* gdb.guile/scm-parameter.exp: New file.

	doc/
	* guile.texi (Guile API): Add entry for Parameters In Guile.
	(GDB Scheme Data Types): Mention <gdb:parameter> object.
	(Parameters In Guile): New node.