Add this matrix and a specified matrix.
static CL_Mat3<Type> CL_Mat3< Type >::add( const CL_Mat3 < Type > & matrix_1, const CL_Mat3 < Type >mpamp; matrix_2); CL_Mat3<Type>& CL_Mat3< Type >::add( const CL_Mat3 < Type > & add_matrix);
Detailed description:
This adds the matrix as follows: this = add_matrix + this