Support for columns definition

[cuchac]

Hello,
we use this library for several years and it is a lifesaver. The only really working solution for fast streaming generation of large XLSX files.

We use our own XLSX base template, but output file is missing columns sizes from the template. The code for preserving column sizes is not present in https://github.com/Polyconseil/xlsx_streaming/blob/master/xlsx_streaming/render.py#L318. I have no problem implementing it. Would that be OK for you?

Is there any reason you discard whole <worksheet> XML from template and picks only some specific information? What if I change the code to preserve everything and just generate new <sheetData>? Something like

yield f'<worksheet xmlns="{OPENXML_NS}" xmlns:r="{OPENXML_NS_R}">\n'.encode(encoding)

for tag in get_all_tags_except_sheetData(openxml_sheet_string):
   yield tag

yield '<sheetData>\n'.encode(encoding)
....... as normal