Request: `#include "biski64.c"` rather than copy-pasting functions

[memphis242]

Thanks @danielcota for this neat PRNG!

I was trying to use it in a project of mine - conficol/src/conficol_shared.c : memset_scramble - but I didn't like the idea of simply copying the functions you have in biski64.c into my project. I'd rather make your repo a submodule and simply #include "biski64.c" to get the function inlining where it needs to be. That also makes it much easier to update this submodule dependency to whatever fixes/upgrades you may make in the future.

The only issue is biski64.c includes a main function to demo its usage, which is handy to see, but it also means my own program's main will clash when I #include "biski64.c" (there can only be one main).

I opened a PR for my proposed fix for this:

• Allow users to #include "biski64.c" without main coming along for the ride #6