Improve indentation of generated Java-code

[mthmulders]

Given a small input file, sample.tt:

const MY_CONSTANT = 42;
typedef long MyLongs[MY_CONSTANT];
struct MyStructure {
     MyLongs myLongs;
};

Invoking Treetop with: bundle exec xdrgen sample.tt -o generated -l java -n generated, it generates this Java source file:

// Automatically generated by xdrgen 
// DO NOT EDIT or your changes may be overwritten

package generated;


import java.io.IOException;

// === xdr source ============================================================

//  typedef long MyLongs[MY_CONSTANT];

//  ===========================================================================
public class MyLongs  {
  private Long[] MyLongs;
  public Long[] getMyLongs() {
    return this.MyLongs;
  }
  public void setMyLongs(Long[] value) {
    this.MyLongs = value;
  }
  public static void encode(XdrDataOutputStream stream, MyLongs  encodedMyLongs) throws IOException {
  int MyLongssize = encodedMyLongs.getMyLongs().length;
  for (int i = 0; i < MyLongssize; i++) {
    stream.writeLong(encodedMyLongs.MyLongs[i]);
  }
  }
  public static MyLongs decode(XdrDataInputStream stream) throws IOException {
    MyLongs decodedMyLongs = new MyLongs();
  int MyLongssize = MY_CONSTANT;
  decodedMyLongs.MyLongs = new Long[MyLongssize];
  for (int i = 0; i < MyLongssize; i++) {
    decodedMyLongs.MyLongs[i] = stream.readLong();
  }
    return decodedMyLongs;
  }
}

Apart from the fact that this code does not compile (#33) it also has some strange indentation choices in its encode and decode methods. This PR fixes that.