Support idemponent (dict) column order for row appending with empty cells

[synergiator]

Currently, you have to append rows exactly following the headers' scheme.

Imagine though a situation where you would like to set cell values in some random order and maybe let some cells empty.

That is, you would just create a dict, fill in some values with headers' keys and pass it to append_row, the logic then figures out dynamically how to proceed.

[pri22296]

How does a separate method append_row_from_dict sound?

[pmury]

great!