Make FsStatusFlags struct fields non-public and add getters

This way new fields can be added later without losing backward compatibility.

src/fs.rs

@@ -38,8 +38,18 @@ impl FatType {
 }
 
 pub struct FsStatusFlags {
-    pub dirty: bool,
+    pub(crate) dirty: bool,
-    pub io_error: bool,
+    pub(crate) io_error: bool,
+}
+
+impl FsStatusFlags {
+    pub fn dirty(&self) -> bool {
+        self.dirty
+    }
+
+    pub fn io_error(&self) -> bool {
+        self.io_error
+    }
 }
 
 pub trait ReadSeek: Read + Seek {}

tests/read.rs

@@ -195,8 +195,8 @@ fn test_volume_metadata_fat32() {
 
 fn test_status_flags(fs: FileSystem) {
     let status_flags = fs.read_status_flags().unwrap();
-    assert_eq!(status_flags.dirty, false);
+    assert_eq!(status_flags.dirty(), false);
-    assert_eq!(status_flags.io_error, false);
+    assert_eq!(status_flags.io_error(), false);
 }
 
 #[test]