Log Message:
Updated meld to 3.15.3.

2016-04-20 meld 3.15.3
======================

  Fixes:

   * Handle unicode dates in non-UTF8 locales in folder comparison (Kai
     Willadsen)
   * Try to auto-detect when to use our dark theme highlighting (Kai Willadsen)
   * After undo/redo actions in file comparisons, place the cursor at the
     natural edit position and scroll it back onscreen (Kai Willadsen)