Fix fatal error on Hair material

fix broken url

This change fix a error on Hair material when the upper value for 'beta_m' or 'beta_n' is greatest than 1.0

Basic converter from nanovdb to pbrt's text format for volumes,
including support for downsampling.

Make capitalization consistent for the [XYZ]Size() methods.
Add PBRT_CPU_GPU to those as well as to BytesAllocated().

Take the incident `IOR` into account for the `CoatedConductorMaterial`

Moved the divides to also cover the case where it works backward
to compute eta/k based on a user-specified reflectance.

This takes the incident index of refraction into account when setting the relative index of refraction for coated conductors.

LLDB DataFormatters (Debug Visualizer) 

Issue #333.

Issue #333.

Silent warning in VDB dependecies

Silence a MSVC warning 4146 caused by NanoVDB code when a unary minus operator is applied to an unsigned type.

Address compile issue with macro expansion for using optixModuleCreate or optixModuleCreateFromPTX

Will hopefully fix issue #329.

Fixes issue #331.

Use the latest CUDA and OptiX releases, prune some old ones.

The OptiX 7.7 build should fail, per bug #731...

Silent build warnings about deprecated 'snprintf'

This directive silences many annoying and perhaps unused warning messages under MacOS arm64 about that a few of printf's are now deprecated

Issue #308.

It's not a very good denoiser and in any case is not described in the book.

(Issue #320)

Fixes #321.

Fix bug in polymorphic_allocator::deallocate

Avoid NaNs when the BSDFSample's pdf is 0.

Addresses #313

No functional changes; just some variable renamings and changes in comments
that correspond to fragment names that were edited.