* Support u8 / u32 indices
* Skip primitives without vertices
* Add support for non-indexed geometry & skipping primitives
* Fix possible memory leak on error
* Use SSkinnedMesh
* Check indices
* Properly mirror node hierarchy
* Update .gitignore
* Reorder includes
* Add some throws for logic errors
* Fix non-indexed geometry winding order, add unit test
* Address code review comments
* Add matrix transform unit test
It is insecure and inconvenient to necessitate installing IrrlichtMt to access the target export. A copy of the export is now placed in the build tree during configuration so that it can be directly accessed from any project by pointing find_package() to look at the IrrlichtMt source directory.