Add this matrix and a specified matrix.
static CL_Mat4<Type> CL_Mat4< Type >::add( const CL_Mat4 < Type > & matrix_1, const CL_Mat4 < Type > & matrix_2); CL_Mat4<Type>& CL_Mat4< Type >::add( const CL_Mat4 < Type > & add_matrix);
Detailed description:
This adds the matrix as follows: this = mult + this