代數題 multiply bug

1. 代數題輸入數學式子時，可以顯示 L^ATEX編譯的結果，連乘時乘號 $\times$... ...$\times$ 會變成 times。
   
2. 程式修改 qtype_algebra.php

   [root@dywang algebra]# diff -uN ../../../mod_tmp/algebra/lang/en/qtype_algebra.php lang/en/qtype_algebra.php 
   --- ../../../mod_tmp/algebra/lang/en/qtype_algebra.php  2013-05-20 16:23:42.000000000 +0800
   +++ lang/en/qtype_algebra.php   2014-10-07 15:30:44.331309454 +0800
   @@ -34,7 +34,7 @@
    $string['missingonearg'] = 'Syntax Error: Operator \'{$a}\' missing its argument';
    $string['missingtwoargs'] = 'Syntax Error: Operator \'{$a}\' requires two arguments';
    $string['morethantwoargs'] = 'Trying to compare a term with more than 2 arguments - no code to handle this case!';
   -$string['multiply'] = '\\\\times';
   +$string['multiply'] = '\\times';
    $string['nargswrong'] = 'Incorrect number of arguments for the term \'{$a}\'';
    $string['noevaluate'] = 'The evaluate method for term \'{$a}\' has not been implemented';
    $string['notopterm'] = 'Syntax Error: Unable to condense to a single, top level operator';
   

3. 再次測試乘號已正常顯示