Add "XLS to CSV" converter to preprocess

[champierre]

It seems that "XLS to CSV" converter is somehow half working.

I tried

dim install https://www.city.chofu.tokyo.jp/www/contents/1489047638868/simple/1.xls -n "東京都調布市市立小・中学校一覧" -p xlsx-to-csv

and the result was only 1.xls was downloaded but it was converted to CSV.
I would like to see that both 1.xls and 1.csv are placed in the data_files folder.

[ryo-ma]

What do you mean that "half working"?
OK. I agree with keeping both files.

This issue is low priority
But, I welcome your contributions