Log Message:
Update contao42 to 4.2.3.

### 4.2.3 (2016-09-06)

 * Do not double URL encode the content syndication links.
 * Use CSS3 transforms instead of transitions to animate the off-canvas navigation.
 * Improve the exception handling when using the resource locator (see #557).
 * Correctly reset the filter menu in parent view.
 * Support all characters but =!<> and whitespace in simple tokens (see \ 
contao/core#8436).
 * Check the user's permission when generating links in the picker (see \ 
contao/core#8407).
 * Handle forward pages without target in the navigation modules (see \ 
contao/core#8377).
 * Provide the same template variables for downloads and enclosures (see \ 
contao/core#8392).
 * Handle %n when parsing date formats (see contao/core#8411).
 * Fix the module wizard's accessibility (see contao/core#8391).
 * Correctly initialize TinyMCE in sub-palettes in Firefox (see contao/core#3673).
 * Validate form field names more accurately (see contao/core#8403).
 * Correctly show the ctime, mtime and atime of a folder (see contao/core#8408).
 * Correctly index changed pages (see contao/core#8439).