reimplement functionality to run whole text search using DFA

shell/search-thread.sml

@@ -2,12 +2,11 @@ structure SearchThread =
 struct
   open CML
 
-  (* Prerequisite to sending message: move buffer to end. *)
   fun loop () =
     let
       val (buffer, dfa, time) = Mailbox.recv SearchMailbox.mailbox
-      val searchList =
-        raise Fail "todo: reimplement full builder for searchList"
+      val iterator = LineGap.makeStringIterator buffer
+      val searchList = SearchList.build (iterator, dfa)
       val msg = InputMsg.WITH_SEARCH_LIST (searchList, time)
       val () = InputMailbox.append msg
     in