Added Matrix.LUPDecompose, Matrix.Determinant, Matrix.swapRows. Changed Matrix.Inverse to use them
Removed == and != operators because m == null is a pain
Changed Matrix.inversible, too
Added MAtrix.InverseAlt
Revert Matrix.Inverse to use m.determinant()
Added sanity checks to Matrix.InverseAlt and switched operator ~ to Matrix.InverseAlt
Added error calculation for Gauss_Seidel_Serial.solve