add ack.h and change format of error again

git-svn-id: https://svn.musicpd.org/mpd/trunk@1327 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/ack.h

@@ -0,0 +1,16 @@
+#ifndef ACK_H
+#define ACK_H
+
+#define ACK_ERROR_NOT_LIST		1
+#define ACK_ERROR_ARG			2
+#define ACK_ERROR_PASSWORD		3
+#define ACK_ERROR_PERMISSION		4
+#define ACK_ERROR_UNKNOWN		5
+#define ACK_ERROR_NO_EXIST		6
+#define ACK_ERROR_PLAYLIST_MAX		7
+#define ACK_ERROR_SYSTEM		8
+#define ACK_ERROR_PLAYLIST_LOAD		9
+#define ACK_ERROR_UPDATE_ALREADY	10
+#define ACK_ERROR_PLAYER_SYNC		11
+
+#endif