fix 100% cpu usage

Makefile

@@ -1,6 +1,6 @@
-all: bin/crossword bin/ssh
+all: bin/crossword bin/crossword-ssh
 
 bin/crossword: main.go puz/puz.go game/game.go
 	go build -o $@ .
-bin/ssh: ssh/main.go puz/puz.go game/game.go
+bin/crossword-ssh: ssh/main.go puz/puz.go game/game.go
 	go build -o $@ ./ssh

ssh/main.go

@@ -56,7 +56,10 @@ func main() {
 		})
 
 		for {
-			scanner.Scan()
+			ok := scanner.Scan()
+			if !ok {
+				break
+			}
 			buffer := scanner.Bytes()
 
 			exited := state.HandleInput(buffer)