Wrong Luxembourg Franc symbol in currency to euro conversion

[Albert Astals Cid]

Please CC me, i'm *not* subscribed to calligra-devel

In sheets/functions/financial.cpp you can see
   else if (cur == "LUX") result = 40.3399;   // Luxembourg
which is wrong since the correct symbol for the old Luxembourg Franc is LUF as 
correctly written in sheets/functions/financial.xml and sheets/Currency.cpp

The question is, do we want to replace LUX with LUF in that function or should 
we add a new else with LUF and leave LUX there in case someone was using it 
wrong?

Cheers,
  Albert