merging to upstream

[illwieckz]

I move the issue there so we can remove the old unvanquished fork.

There was some PR made on BinomialLLC's side but they were not merged:

• [ ] BinomialLLC/crunch#12
• [x] BinomialLLC/crunch#13
  • https://github.com/BinomialLLC/crunch/pull/25 by someone else was merged instead
• [ ] BinomialLLC/crunch#14

Since they officially stated they don't support crunch any more, it's likely to never happens.

Then Unity people took the code and improved it a lot, so I replayed the commits on their tree with hope they will upstream them, I also added another commit to fix an issue they introduced:

• [ ] Unity-Technologies/crunch#2
• [ ] Unity-Technologies/crunch#3
• [ ] Unity-Technologies/crunch#5
• [ ] Unity-Technologies/crunch#7
• [ ] Unity-Technologies/crunch#8
• [ ] Unity-Technologies/crunch#9
• [ ] Unity-Technologies/crunch#10
• [ ] Unity-Technologies/crunch#13

Basically the commits fix compilation on 64 bit, fix compilation on Linux, fix build outside of Visual Studio, and add an improvement: to renormalize on the top of mip-level too using the -rtopmip option with the --renormalize one, allow user-defined CRND_ASSERT, fix malloc on macOS and FreeBSD.