MDL-20204 first batch of major theme changes, some regressions are still there, expect more changes and improvements soon; see tracker for details and list of subtasks

MDL-20700 coding style cleanup - cvs keywords removed, closign php tag removed, trailing whitespace cleanup

MDL-17458 upgrade logging implemented + a lot more refactoring + exceptions implemented in install/upgrade code + lang pack cleanup + some more improvements

MDL-17457 migrated all modules to new db/install.php; added upgrade.txt file for devs converting contrib modules