tr_torrentIterate ability to stop torrents

[oleo]

I think that tr_torrentIterate() should be modified in such way that callback function can stop and delete torrent. Here is modification proposal:

void tr_torrentIterate( tr_handle_t * h, tr_callback_t func, void * d )
{
    tr_torrent_t * tor, *next;

    for( tor = h->torrentList; tor; tor = next )
    {
        next = tor->next;
        func( tor, d );
    }
}

func( tor, d ); can now free(tor) without creating segfault when iterating through a list.

[livings124]

Done in [751]/