* cmds.c (overwrite_binary_mode): Deleted; this implements the

* cmds.c (overwrite_binary_mode): Deleted; this implements the
	wrong feature.
	(Qoverwrite_mode_binary): New variable.
	(internal_self_insert): If current_buffer->overwrite_mode is
	`overwrite-mode-binary', do as overwrite_binary_mode used to.
	(syms_of_cmds): Remove defvar of overwrite_binary_mode; initialize
	Qoverwrite_mode_binary.
	* buffer.c (syms_of_buffer): Doc fix for overwrite_mode.
	* buffer.h (struct buffer): Doc fix.