Merged from 1.5 branch to trunk, all changes from 1821 to 1835. Mostly warning fixes, GL ASM shaders repaired, d3d9 RTTs less memory consuming, skinned mesh bboxes updating.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1837 dfc29bdd-3216-0410-991c-e03cc46cb475