This should increase a bit the compability with Excel files

This is related to the previous commit

nsids are random identifiers, usually used to ease merging
between documents, and can trivially be used for fingerprinting.

Brolf authored 6 years ago and georg committed 6 years ago

Closes #96

This should make easier to get more metadata from
archive-based file formats.

intrigeri authored 6 years ago and jvoisin committed 6 years ago

This should closes  #90

We didn't take the whitelist into account while
removing dangling files from [Content_types].xml

- Replace some class members by instance members
- Don't thread the cleaning process anymore for now

MS Office XML rsid is a "unique identifier used to track the editing session
when the physical character representing this section mark was last formatted."

See the following links for details:
- https://msdn.microsoft.com/en-us/library/office/documentformat.openxml.wordprocessing.previoussectionproperties.rsidrpr.aspx
- https://blogs.msdn.microsoft.com/brian_jones/2006/12/11/whats-up-with-all-those-rsids/.

In XML, the order of the attributes shouldn't be meaningful,
however, MS Office sorts attributes for a given XML tag
differently than LibreOffice.

Closes #60

Note: this changeset also ensures that clean.cleaned.docx is removed
up after the pytest is over.