BigInt.opCmp

auto x = BigInt("100");
auto y = BigInt("10");
int z = 50;
const int w = 200;

assert(y < x);
assert(x > z);
assert(z > y);
assert(x < w);

auto x = BigInt("0x1abc_de80_0000_0000_0000_0000_0000_0000");
BigInt y = x - 1;
BigInt z = x + 1;

double d = 0x1.abcde8p124;
assert(y < d);
assert(z > d);
assert(x >= d && x <= d);

// Note that when comparing a BigInt to a float or double the
// full precision of the BigInt is always considered, unlike
// when comparing an int to a float or a long to a double.
assert(BigInt(123456789) < cast(float) 123456789);