Providing User entity support

This provides a way to compare the main user properties as well as the additional fields on user objects.

It adds a new entity settings local tab.

Example usage

Two users with a couple of fields (A name and file field).

$account_a = user_load(1);
$account_b = user_load(5);
module_load_include('pages.inc', 'diff');
$header = _diff_default_header(entity_label('user', $account_a), entity_label('user', $account_b));
$rows = diff_entity_body_rows('user', $account_a, $account_b);

$build['diff_table'] = array(
  '#theme' => 'table',
  '#header' => $header,
  '#rows' => $rows,
  '#attributes' => array('class' => array('diff')),
  '#colgroups' => _diff_default_cols(),
  '#sticky' => FALSE,
);

print drupal_render($build['diff_table']);

Which outputs: