O.from_number() does not work for "big" numbers

[FilippoTrotter]

The O.from_number() method from the file src/zen_octet.c, used to convert an integer into octets, seems to not work correctly with sufficiently large numbers. Specifically, I've noticed the issue arises with numbers larger than 2^25.The problem appears with odd numbers. For example, the following test is passed by the function, which clearly should not happen.

assert(O.from_number(2^25-1)==O.from_number(2^25))
assert(O.from_number(2^25-3) == O.from_number(2^25-4))

[matteo-cristino]

This seems due to the combination of lua_Number as type in output of lua_tointegerx and the floorf function (Could not find any documentation of it online 🤷). Not totally sure why, but replacing lua_Number to lua_Integer and removing the floorf function make it work as intended.

[matteo-cristino]

first draft fix here fix/oct_from_number