gdb/

gdb/
	* inferior.h: Forward declare struct ui_out.
	Forward declare struct private_inferior.
	(struct inferior): New.
	(init_inferior_list, add_inferior, add_inferior_silent)
	(delete_inferior, delete_inferior_silent, detach_inferior)
	(gdb_inferior_id_to_pid, pid_to_gdb_inferior_id, in_inferior_list)
	(valid_inferior_id, find_inferior_pid): New functions.
	(inferior_callback_func): New typedef.
	(iterate_over_inferiors, print_inferior, have_inferiors)
	(current_inferior): New functions.
	* inferior.c: New file.

	* Makefile.in (SFILES): Add inferior.c.
	(COMMON_OBS): Add inferior.o.

gdb/doc/
	* gdb.texinfo (Inferiors): New section.