Add function to be able to add cell comments
Created originally on Bitbucket by gerigk
As posted in the mailing list:
I found out that comments are stored in a seperate .XML (if you rename the xlsx and unzip it) in the "xl" folder.
An .XML is created for each worksheet
"comments1.xml" inside the "xl" folder. In the worksheets folder we get an entry inside the "_rels" in sheet1.xml.rels " " for the comments XML file
The comments1.xml looks like this
This is a comment