Rename functions to be more idiomatic.

lib/aoc.mli

@@ -1,11 +1,11 @@
-val nums_from_string : string -> int list
+val ints_of_string : string -> int list
 (** [nums_from_string s] takes a string of space separated integers and gives
     back a list of the integers. *)
 
 val distance1 : int -> int -> int
 (** [distance1 a b] returns the absolute difference between [a] and [b]. *)
 
-val strings_from_file : string -> string list
+val strings_of_file : string -> string list
 (** [strings_from_file fname] returns a list of strings from the file 
     [fname].  Each string represents a line from the file. *)