Implement dynamic material example and dynamic geometry example

[keckj]

This pull request add the support for the following:

New examples

• dynamic_geometry.py
• dynamic_materials.py

Add support for interactive OpenGL examples:

• Added the optix.sutil submodule to mimic the optix SDK sutil API (optix/SDK/sutil).
• Added sutil.camera.Camera which implements all sutil/Camera.h features.
• Added sutil.camera.Trackball which implements all sutil/Trackball.h features.
• Added sutil.cuda_output_buffer.CudaOutputBuffer which implements sutil/CUDAOutputBuffer.h features (currently only supports CUDA_DEVICE mode, GL_INTEROP support may be added later once available in cupy).
• Added sutil.gl_display.GLDisplay which implements all sutil/GLDisplay.h features.
• Added sutil.gui which implements some GUI features of sutil/sutil.h (init_ui, display_text, display_stats).
• Added sutil.vecmath which implements basic vector operations (dot product, cross product, normalize, length).
• The python port closely follows the SDK by using the exact same graphical APIs:
  1. OpenGL -> PyOpenGL
  2. glfw -> pyglfw
  3. imgui -> pyimgui, pyimgui[glfw]

New features:

The two new examples required some additions to the existing wrapper:

• Add a way to retrieve default build options to build custom user kernels: module.pyx:get_default_nvrtc_compile_flags().
• OptixBuildInputInstanceArray.instances is now public to be able to update instances directly in python.
• Instances that are modified in python in host memory can be updated in device memory with build.pyx:BuildInputInstanceArray.update_instance().
• Allow to update traversable object reference and handle with build.pyx:BuildInputCustomPrimitiveArray.update_traversable().
• Get a view on an instance transform matrix device memory with build.pyx:BuildInputInstanceArray.get_transform_view().
• SbtRecord now store a list of ProgramGroup instead of a single ProgramGroup.
• Program groups can now be updated with struct.pyx:SbtRecord.update_program_group().

Bug fixes

• Fixed optix assertion in BuildInputCustomPrimitiveArray due to a CuPy stride bug when there was only one AABB passed as a numpy array (see Unexpected stride when performing cupy.asarray on numpy.ndarray with leading dim 1 cupy/cupy#5897). This bug may affect other strides.
• Fixed default visibility mask value from 2**(sizeof(unsigned int) * 8) - 1 to 2**max_visibility_mask_bits - 1.
• Fixed Cython error on negative python int to unsigned int assignment (OPTIX_PRIMITIVE_TYPE_FLAGS_TRIANGLE = 1 << 31 is a negative C int affected to a python integer (enum.IntEnum.value). Optix expects unsigned int flags in its structs, which led to a Cython conversion error: cannot affect negative python int to unsigned int. This bug may affect other enums.
• Other small fixes

[mortacious]

Wow, really nice work!
I will review and merge this as soon as possible once I get back from my vacation.