Improve pretty printing done by MXSerializer

• Patch Submitted:

  Yes

The MXSerializer commonly used by the Modello generated writers produces something like

<?xml version="1.0" encoding="UTF-8"?><metadata>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-jxr-plugin</artifactId>
  <version>2.1</version>
  <versioning>
    <latest>2.1</latest>
    <release>2.1</release>
    <versions>
      <version>2.0</version>
      <version>2.1</version>
    </versions>
    <lastUpdated>20070407095323</lastUpdated>
  </versioning>
</metadata>

It would be cool if there were newlines after the XML declaration and at the end of file.