svg fixes (not)

[mihirsamdarshi]

This PR contains fixes for a number of issues. It resolves:

• Allow sheet names to be case-insensitive on Excel input workbooks #732, where inputting a workbook was case-sensitive for sheet names
• Create collapsible sections and organize side bar #803 a bug where the checkbox was not initialized as it should've been
• When enabling colored edges after disabling, the graph does not maintain the correct normalization max #809 a bug where after re-selecting edge weight coloring, the edge weights would be off
• Displayed demo file name needs to be restored to the original behavior #810 the demo files displayed their path and not name in the top bar
• (anticipated) Export vector image to pdf and/or svg in a format that can be read by Adobe Illustrator #59 svg not exporting properly to Illustrator

[dondi]

Looks good as a work in progress; will merge so later changes can show up better.