There is a error in fitQuadric at master branch

[vic1314]

Describe the bug
Neighbourhood::computeQuadric are fitting a quadric equation z = c1 + c2x +c3y + c4xx + c5xy + c6 * y*y.
but the code is

	//for every points
	{
		double* _A = A.data();
		double* _b = b.data();
		for (unsigned i = 0; i < count; ++i)
		{
			CCVector3 l = toLocalOrientation * (*m_associatedCloud->getPoint(i) - *G);

			*_A++ = 1.0;
			*_A++ = l.x;
			*_A++ = l.y;
			*_A = static_cast<double>(l.x)*l.y;  //###here is an error ,suppose to be *_A = static_cast<double>(l.x)*l.x;
			//by the way, we track the max 'X' squared dimension
			lmax2 = std::max(lmax2, *_A);

			++_A;
			*_A++ = static_cast<double>(l.x)*l.y;
			*_A = static_cast<double>(l.y)*l.y;
			//by the way, we track the max 'Y' squared dimension
			lmax2 = std::max(lmax2, *_A);
			++_A;

			*_b++ = l.z;
			//and don't forget to track the max 'Z' squared dimension as well
			lmax2 = std::max(lmax2, static_cast<double>(l.z)*l.z);
		}
	}

How to reproduce

Expected behaviour

Additional context

Your environment

• CCCoreLib Version (or git hash/tag):
• OS & Version:
• Qt Version (if compiling w/Qt):
• TBB Version (if compiling w/TBB):