Case-insensitivity for all worksheets in the Excel workbook

[kdahlquist]

Issue #732 addressed the case of sheet names being case-insensitive for the "network" sheet. However, we need to decide and then implement if we will allow other sheet names to be case-insensitive as well.

I believe GRNmap is going to expect them to be all lower case (but I would need to verify that). When GRNmap outputs files, it does make all the names lower case.

It is in the situation where users are making Excel workbooks from scratch that this will come up.

One of the downstream applications of the Export to Excel function is to act as in input workbook validator for GRNmap. For example, if a user uploads a workbook that has "Network" instead of "network" for the network sheet, GRNsight will accept it, but fix the tense upon export.

I don't know if this is something we have time to do before the end of the semester. Because it involves changing formats, I want to make sure that have all the proper tests in place.

[mihirsamdarshi]

case-insensitivity was implemented for network_optimized_weights sheets when the change for the network sheet was made

[kdahlquist]

@kdahlquist should look into this one and see if it can be closed.