Change io crate & add a small shell

crates/bffs/src/boot_sector.rs

@@ -1,5 +1,6 @@
-use crate::error::Error;
-use io::{Read, ReadLeExt};
+use io::Read;
+
+use crate::io_ext::ReadLeExt;
 
 #[derive(Debug, Clone, Copy)]
 pub struct Fat32BootSector {
@@ -94,7 +95,7 @@ impl Fat32BootSector {
 }
 
 impl Fat32BootSector {
-    pub fn deserialize<T: Read>(disk: &mut T) -> Result<Self, Error<T::Error>> {
+    pub fn deserialize<T: Read>(disk: &mut T) -> Result<Self, io::Error> {
         let mut jump_boot = [0u8; _];
         disk.read_exact(&mut jump_boot)?;
         let mut oem_name = [0u8; _];