Encoding parameter only for reading, not for writing

[alper]

I think the encoding parameter should only be used to read in files. Anything produced should be in utf-8 regardless.

I have to set the parameter because my bank returns files in windows-1252 but I have zero interest in producing a file in that same format. I think that may be the case for more users.

Alternatively, there could be a new parameter to override the output encoding.

[reubano]

Good point! Not sure when I'll have the time to address this. PRs welcome of course :).