Nim changes

[def-]

• Made the Nim code simpler, still runs just as fast for me
• Cleaned the code up a bit
• Renamed from Nimrod to Nim
• Added clang as backend (mostly faster with Nim)

Also, this benchmark depends a lot on the RNG used, doesn't it?

[nsf]

It doesn't depend on RNG. RNG is used only during initialization. Unless RNG is extremely slow, you won't see any difference.