flush writer, makes partial deserialization a bit less likely

src/entry_writer.rs

@@ -20,7 +20,8 @@ impl<'a, W: Write> EntryWriter<'a, W> {
 
     fn write_entry(writer: &mut W, entry: &Entry) -> io::Result<()> {
         let serialized = serde_json::to_string(entry).unwrap();
-        writeln!(writer, "{}", serialized)
+        writeln!(writer, "{}", serialized)?;
+        writer.flush()
     }
 
     pub fn write_entries<I>(writer: &mut W, entries: I) -> io::Result<()>