Provides the package file data model and allows the client to create/modify symbian package file.

Create a new package file:

    	PackageFile file = new PackageFile();
    	file.addStatement(new Vendor("NOKIA"));
    	// adds other statements
    	...
    	file.save(new File("mynewpackage.pkg"));

Load from existing package file:

    	PackageFile file = new PackageFile();
    	file.load(new File("mypackage.pkg"));
    	// reads the statements
    	Header header = file.getStatement(Header.class);
    	header.setUid("0x12345678");
    	file.save(new File("mypackage.pkg"));