string.c -- some common string routines all rolled into one package

	char *strcpy(dest, src)
	register char *dest, *src;

	char *strncpy(dest, src, len)
	register char *dest, *src;

	char *strcat(dest, src)
	register char *dest, *src;

	char *strncat(dest, src, len)
	register char *dest, *src;

	strcmp(a, b)
	register char *a, *b;

	strncmp(a, b, len)
	register char *a, *b;

	strlen(str)
	register char *str;

	char *index(str, c)
	register char *str; register int c;

	char *rindex(str, c)
	register char *str; int c;