harden ipc and frontend recovery

dat.h

@@ -126,12 +126,20 @@ struct Drawcmd
 };
 
 typedef struct Keyreq Keyreq;
+typedef struct Keyres Keyres;
+struct Keyres
+{
+	int	eaten;
+	Str	commit;
+	Str	preedit;
+};
+
 struct Keyreq
 {
-	int	fd;
 	u32int	ks;
 	u32int	mod;
-	int	want;	/* nonzero: append preedit after commit */
+	int	want;	/* nonzero: include preedit in reply */
+	Channel	*reply;
 };
 
 typedef struct Dictreq Dictreq;