Use from_be_bytes in one more place.

src/util.rs

@@ -41,7 +41,7 @@ pub fn read8<R>(reader: &mut R) -> Result<u8, io::Error> where R: io::Read {
 pub fn read16<R>(reader: &mut R) -> Result<u16, io::Error> where R: io::Read {
     let mut buf = [0u8; 2];
     reader.read_exact(&mut buf)?;
-    Ok(((buf[0] as u16) << 8) + buf[1] as u16)
+    Ok(u16::from_be_bytes(buf))
 }
 
 // This function must not be called with more than 4 bytes.