First round of override updates.
Some fixes:
Added get/setCurrentRenderPass to scene manager (internally renamed, exposed)
Removed destructor from light scene node.
Removed getType calls from archive loaders (one file archives have this)
Removed some internal exposures and virtual attributes for protected classes

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@4543 dfc29bdd-3216-0410-991c-e03cc46cb475