csvjoin should throw more explicit errors when column names don't match because of whitespace

Created by: facundofarias

I was trying to perform a csvjoin, and I was getting the following output: Column identifier "xxx" is neither an integer, nor a existing column's name. The thing was, that the field name contained a blank space before the name. Perhaps it could be helpful to trim all the blank spaces at the beginning and at the end of the column name. What do you think? If you agree and give me some hints, I can do it :)

Thanks