This should improve epub support

This is now required by ffmpeg

This should increase a bit the compability with Excel files

This commit takes care of removing residual metadata
added by mat2 during the cleaning of pdf.

Mypy doesn't like some annotation in web.py,
this commits aims at pleasing it.

Mounting new, empty filesystem on /tmp makes impossible to use mat2 for manipulating files stored there. Especially it breaks running tests while creating package and using /tmp as temporary builddir which is common setup in Arch Linux:
https://aur.archlinux.org/packages/mat2/#comment-721221

georg authored 5 years ago and jvoisin committed 5 years ago

Closes #131

Due to bubblewrap's pickiness, mat2 can now be run
without a sandbox, even if bubblewrap is installed.