Api/morechildren

Example:

    var superAgentRequest = rereddit.morechildren('t3_1brr67',
        ['c99mdak', 'c99miwx', 'c99mxwa']).end;

or

    var superAgentRequest = rereddit.morechildren('t3_1brr67',
        'c99mdak,c99miwx,c99mxwa').end;