Renamed BlockReader to MetadataReader (more correct)

SOME work on fragments (not working still...)

filereader.go

@@ -0,0 +1,17 @@
+package squashfs
+
+type FileReader struct {
+	r            *Reader
+	data         *DataReader
+	fragmentData []byte
+}
+
+//TODO: Yes
+
+func (r *Reader) ReadFile(location string) (*FileReader, error) {
+
+}
+
+func (f *FileReader) Read(p []byte) (int, error) {
+
+}