Use XXHash64 for all hashes

[mbouaziz]

Currently, we have crc64 to hash strings and murmur to combine hashes. Both are non-cryptographic. XXHash is faster than both with similar good properties. Crc64 could be better at detecting small changes but that's not what we're asking for here.

Any reason not to switch to xxhash for everything?

[pikatchu]

I thought I fixed that. Where do you still see use of crc64 for strings?

[mbouaziz]

I'm talking about Skip, not skjs

[pikatchu]

Ahhhh. Sorry I am on my phone, didn't pay attention to the repo.

Yes we could switch to xxhash for everything. But this is low-pri no?

[mbouaziz]

Kinda low-pri, but it'd:

• make all Skip programs faster
• simplify SkJS