equals method
Implementation
bool equals(ECPointFp other) {
if (other == this) return true;
if (isInfinity()) return other.isInfinity();
if (other.isInfinity()) return isInfinity();
final u = (other.y!.toBigInteger() * z - y!.toBigInteger() * other.z) % curve.q;
if (u != BigInt.zero) return false;
final v = (other.x!.toBigInteger() * z - x!.toBigInteger() * other.z) % curve.q;
return v == BigInt.zero;
}