Improve keyboard management in FB device. Thanks to @glemercier for patch.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code@4776 dfc29bdd-3216-0410-991c-e03cc46cb475
Added OGLES2 support for FB device. Thanks to @glemercier for patch.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code@4777 dfc29bdd-3216-0410-991c-e03cc46cb475