This will let users read a file that contains data that are not properly
supported and write them back to a new file untouched.
- load workbookProtection attributes
- save loaded pageSetup[r:id]
- save loaded sheet's AlternateContent
- save loaded unparsed VmlDrawings
- save loaded drawing files `rId`
- save loaded draw's AlternateContent
- save loaded control properties
- save loaded printer settings
- save loaded unparsed override content types (for ctrlProp, ...)
Closes#435
Adrien Crivelli