Enable autoconvert in GssResourceGenerator.

This is still guarded by a flag and needs to be turned on by each app.

fixes #108
```JAVA
String gss = new Css2Gss(stylesheet, new PrintWriter(System.err), extractContantNames, true).toGss();
String fileName = stylesheet.getFile() + "[auto-converted to GSS]";
sourceCodes.add(new SourceCode(stylesheet.getFile(), gss));
```

So I could change the LoggerErrorManager to not display the line and column info (because there are not relevant) when the file name ends with "[auto-converted to GSS]".