Philippe 08/07/2016: lfi2cdf: multiple bug corrections:

* return is not allowed in main program => stop
* number of variables to be read and written was not computed correctly
* name of the outputfile is now correct
* treat correctly the last variable given with -v option
* correct bugs if LOWMEM is set (variables with length=1, reading of TEXT variables)
* correct types when LFI_INT is 8