New default is that the system decides itself.
Reason is that X11 didn't like the last change (disabling it on start) too much and we got messed up title-bars.
Or at least on some Window Managers. Which makes sense as X11 really requires Windows to be resizable in Windowed mode.
git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6196 dfc29bdd-3216-0410-991c-e03cc46cb475