fat_io_lib finally works, implement virtual partition devices, manage devices via string keys

include/devices.h

@@ -0,0 +1,19 @@
+#ifndef _DEVICES_H
+#define _DEVICES_H
+
+/* terminal device */
+#define TERMINAL_PUTSTR 0
+
+/* keyboard device */
+#define KB_READ_KEY 0
+
+/* drive devices */
+#define XDRV_TYPE_RAMDRV  0
+#define XDRV_TYPE_PARTDRV 1
+#define XDRV_GET_SIZE         0
+#define XDRV_GET_SECTOR_SIZE  1
+#define XDRV_GET_DEVICE_TYPE  2
+#define XDRV_READ             3
+#define XDRV_WRITE            4
+
+#endif // _DEVICES_H