Support for large document (> 10 MB)#509

The Google API only allows for exporting 10MB files, allow >10MB files to be viewed in the wiki.

Technical details:

• It is possible to support using the html exportLink for private files
• Optionally, it is possible to iframe the mobilebasic?rm=minimal view for public files

Support added for 10MB public/shared files.

Closing this. Will reopen for private documents as it’s a larger piece of work.