It's no longer enabled by default as it causes some costs to all texture switches.
Thanks @ edo9300 for reporting (http://irrlicht.sourceforge.net/forum/viewtopic.php?f=7&t=52721)
git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6219 dfc29bdd-3216-0410-991c-e03cc46cb475