Signed modulo behavior

[johnmcfarlane]

Surprisingly, I don't think this is supported. E.g.

using modulo_integer = cnl::overflow_integer<int, cnl::modulo_overflow_tag>;
using numeric_limits = cnl::numeric_limits<modulo_integer>;
static_assert(identical(numeric_limits::lowest(), numeric_limits::max() + 1));

Add this tag!