Started to make matrix4 a template to allow for better adaption. Due to renaming of the template the original matrix4 type is still the f32 version of the matrix. I had to remove some forward declarations, though as I did not want to add the template declaration into other headers.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@675 dfc29bdd-3216-0410-991c-e03cc46cb475