Remove lot's of setFocus and removeFocus calls. Also several places where elements check if they have the focus inside events.
Slightly risky change - but it's hard to improve all this without cleaning it up first. And most elements should _not_ be responsible for their 
own focus but the guienvironment should do that (and does do it).


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@4757 dfc29bdd-3216-0410-991c-e03cc46cb475