Zero-cell rows fail in XLSX

[chrisgraham]

A row must have at least one cell, to avoid a repair error in Excel.

API users may add empty rows as spacers.

See my simple change here:
https://github.com/ocproducts/spout/commit/d2029a084fe45e9902e948fe5f1b6ef0cceec6a8

[adrilo]

@chrisgraham, I pushed a fix for that in #13 : aebdd1a

I took a slightly different approach though: I moved the logic to the parent class so that it is applied to all file types. And I figured that passing an empty row ([] not ['']) is not valid and should not result in a blank row being added. Instead, if you do $writer->addRow([]), it does nothing.

I like this approach better because I think [] and [''] represents 2 different things and should therefore be treated differently. What do you think?

[chrisgraham]

I think that's reasonable. Either way the user has choice and no corrupt output.

[adrilo]

Cool! Closing this issue then.