Update hash function to use primes

[ybrunken]

19349663 is not a prime. 19349663 = 41×471943

The number set is like the one proposed in "Optimized Spatial Hashing for Collision Detection of Deformable Objects". Also here 19349663 is stated to be prime.
In "Real-time 3D Reconstruction at Scale using Voxel Hashing", the non-prime is exchanged with 19349669

[nachovizzo]

Hello, @ybrunken. Thanks again for contributing. We are indeed aware of the non-primeness of the numbers. Indeed @benemer is already updating OpenVDB, where we originally took inspiration for the hashing function at AcademySoftwareFoundation/openvdb#1626

If I may, I would like to ask: Did you experience any improvement? After changing the function ourselves, we couldn't really see any difference in runtime/accuracy (we also did not instrument the hashing library at all). This question is out of curiosity only

Thanks!