molecular_dynamics_cells.cpp initializes reference from temporary

[LegalizeAdulthood]

In the following code:

        interaction_functor( hash_vector const& cells_begin , hash_vector const& cells_end , hash_vector pos_order ,
                            point_vector const&x , point_vector const& v , params const &p )
        : m_cells_begin( cells_begin ) , m_cells_end( cells_end ) , m_order( pos_order ) , m_x( x ) , m_v( v ) ,
        m_p( p ) { }

The member variable m_order, which is declared as:

        hash_vector const &m_order;

is initialized from the constructor function call argument hash_vector pos_order, which is a temporary, so that when the constructor exits, the member variable is holding a reference to junk. This results in the following line of code indexing an empty hash_vector and asserting under MSVC:

                        if( m_order[ ii ] == pos_hash ) continue;

I believe the correct fix is to change the type of the parameter to const hash_vector &. If I do this locally, then the assert doesn't fire. Pull request to follow.