Change API of IVideoDriver drawStencilShadowVolume method to take an array of vectors instead of just the pointer and the number of vertices. We have this information anyway, so make us of it.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3957 dfc29bdd-3216-0410-991c-e03cc46cb475