Returns submitdata either as scalar, array or list. In case of list the values
are returned as a string with the values concatenated by comma.

Examples:

// Get as scalar: Optionally pass a default value as second parameter.
// If no default is provided, it will return NULL if no value was submitted

    $myval = ff_getSubmit('myvar');        // return NULL if not submitted

    $myval = ff_getSubmit('myvar',1);      // return 1 if not submitted

    $myval = ff_getSubmit('myvar','foo');  // return 'foo' if not submitted

    ff_query(
        "insert into #__mytable(id, name) ".
        "values ('".
            ff_getSubmit('id').", ".
            ff_getSubmit('name','unknown').
        "')"
    );

// Get as array: Pass FF_ARRAY as second Parameter

    $myarr = $ff_getSubmit('myarr', FF_ARRAY);

    foreach ($myarr as $myval) ...

// Get as list: Pass either FF_LIST, FF_SLIST or FF_DLIST as 2nd parameter.

    // FF_LIST will return numeric data unquoted and strings in single quotes:
    //    1,2,'a',4

    // FF_SLIST will return all data single quoted:
    //    '1','2','a','4'

    // FF_DLIST will return all data double quoted:
    //    "1","2","a","4"

    ff_query(
        "delete from #__mytable ".
        "where id in (".ff_getSubmit('itemlist',FF_LIST).")"
    );