Massive improvements to NanoVDB

[kmuseth]

Massive dump of improvements to NanoVDB:

• Minor version changed from 4 to 6 (major version is unchanged since the ABI is preserved)
• Transition from C++11 to C++17 in NanoVDB.h and its tools
• New (backwards compatible ) file format that allows serialized grids to with streamed directly to file without headers
• Several new ways to construct and modify NanoVDB grids on the GPU
• New device function to convert points into a compact grid: nanovdb::cudaPointsToGrid
• Improved and renamed device function that converts voxels into a grid: nanovdb::cudaVoxelsToGrid
• Introduced a new extendable API for acceleration of custom random-access methods, e.g. getValue(ijk)
• Index grids in 4 flavors (Index, OnIndex, IndexMask, and OnIndexMask)
• Introduced new (dummy) build-type nanovdb::Points and nanovdb::GridType::PointIndex
• Introduced new types nanovdb::GridType::Vec3u16 and nanovdb::GridType::Vec3u8 used for compressed representations of point coordinates as blind data
• CreateNanoGrid.h is replacing GridBuilder.h, IndexGridBuilder.h and OpenToNanoVDB.h
• Moved CudaDeviceBuffer.h to cuda/CudaDeviceBuffer.h
• Added cuda/CudaUtils.h and cuda/GpuTimer.h with cuda utility functions
• Added cuda/CudaPointToGrids.cuh that constructs device grids from lists of points or voxels
• Added cuda/CudaIndexToGrid.cuh that converts IndexGrids and values into regular Grids
• Added cuda/CudaSignedFloodFill.cuh that performs signed-flood filing on SDF on the GPU
• Added cuda/CudaAddBlindData.cuh that adds bind data to an existing grid on the GPU
• Added cuda/CudaGridChecksum.cuh that computes CRC32 checksums of grids on the GPU
• Added cuda/CudaGridHandle.cuh that handles grids on the GPU
• Added cuda/CudaNodeManager.cuh that constructs a NodeManager on the GPU
• Added cuda/CudaGridStats.cuh that computes grid statistics on the GPU
• The move constructor in GridHandle now requires the GridBuffer to actually contain a valid grid
• Added new types: Ve4f, Ve4d, ValueIndex, ValueOnIndex, ValueIndexMask, and ValueOnIndexMask
• Major improvements to GridBuilder.h, which allows user to construct grids with random access on the host
• Numerous improvements in NanoVDB.h: e.g. Customizable get/set methods on ValueAccessor, BitFlags, transform(Map), expandAtomic(BBox), expandAtomic(Coord), intersectAtomic(BBox), pi(), BuildTraits, more documentation, Mask:: DenseIterator, Mask:: setOnAtomic,Mask:: setOffAtomic, Map constructors, DataType are now public vs private in all node types, GridMetaData can now be copied
• PNanoVDB.h is now in sync with NanoVDB.h
• Added PrefixSum.h for concurrent computation of prefix sum on the host
• Primitives.h can now create grids on the CPU with SDF, FOG and point of torus

[kmuseth]

I'm getting weird compiler errors in tbb when building linux-nanovdb:cxx:clang++-Debug/Release. Any ideas what's causing this issue? Clearly it has nothing to do with my code :)

[kmuseth]

Lets make sure we squash all these commits before we merge this!

don't know how to do that after the push. Also don't understand why this is a blocking request

[Idclip]

Lets make sure we squash all these commits before we merge this!

don't know how to do that after the push. Also don't understand why this is a blocking request

Because the VDB commit history should be as clean as possible, not full of "wip fix" commits and not retroactively fixed once pushed to master

squash and merge