Bugfixing and cleanup

* Updated Viewer name to match nvpro-pipeline
* Updated default material path to find the xml effects
* Switch to rix:ubo140 as default shader manger for the Viewer
* Fixed conversion from bool/uint8/uint16 to uint32 for UBO/SSBO uploads in dp::rix::gl
* Added GPU affinity enumeration support to dp::gl::RenderContext
* Refactor DrawableManager to reduce dependencies on the SceneTree
* Fix Memory leaks in 3DSLoader
* Fix Texture*::setImage didn't pass mipmap level when uploading textures
* dp::util::getPlugInterface is now using SmartPtrs for the Plugins