Make checksum comparisons more robust to insignificant file changes

[ezwelty]

The archiving process compares file checksums and only stores the new file if it does not match an existing file in the archive. This protects from unnecessary duplication, but some source files include information like timestamps such that they always appear new. Perhaps this could be addressed by applying small tweaks to the downloaded file before calculating the checksum.

Files

• ArcGIS API: Strip timestamps from response (GML, JSON?). Download as CSV if supported?
• WFS: Strip timestamps from response (GML, JSON). Download as CSV if supported?

Web page

• MHTML: Strip timestamp and de-randomize boundary hash
• HTML: Testing needed
• PDF: Testing needed
• PNG: Testing needed