problem when using non-interctive terminal (like with docker) which shutil return terminal size 0,0

[gilby2]

In this case, the terminal size limits any size change using the plotsize function.
Therefore the better implementation is to check for zeros and return Nones.
Another fix is needed in the default vars names.

[piccolomo]

Just to update and apologise: I have been quite busy rewriting the package from ground up and will update.