Merged revisions 2892:2947 from 1.6 branch. Mainly GUI fixes. Cylinder texturing enhanced. WIN64 defines everywhere also use _WIN64. Code layout and documentation updates.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@2948 dfc29bdd-3216-0410-991c-e03cc46cb475