Added new logo

See merge request !3

Nautilus extension: avoid spamming the logs due to missing method.

See merge request !4

Without this change I see a dozen or so warnings in the Journal:

  nautilus_menu_provider_get_background_items: assertion
  'NAUTILUS_IS_MENU_PROVIDER (provider)' failed

Nautilus upstream developers are going to discuss if/how they want to address
this on their side; in the meantime they recommend simply adding a no-op method
to silence the logs, so here we go.

This reverts commit d054e313.

os.path.join is *not* suitable for concatenating parts of the basename of
a file.

Closes: #11526

It was broken since commit 0d1fe255,
i.e. in the MAT 0.6 and 0.6.1 releases.

The impact is: the MAT extension for Nautilus fails to clean metadata,
without making the user aware of it.

This bug was discovered by the Tails contributor sajolida, and initially
reported to Debian as https://bugs.debian.org/858058.

The long-term goal is to use nose2 for testing

Changing "adding unsupported files" to "deleting unsupported files".
UX people told me that it's more clear this way.

This should close https://labs.riseup.net/code/issues/10839

Thanks to intrigeri for the idea

This should close https://labs.riseup.net/code/issues/10838

This should fix https://labs.riseup.net/code/issues/10065

There is _no_ image support without exiftool, and _no_ audio support
without mutagen. Not "limited" support.

I forgot to add `gi.require_version('Poppler', '0.18')` everywhere,
and `gi.require_version('Gtk', '3.0')` in mat-gui too

Closes https://labs.riseup.net/code/issues/10550
Also known as "pygi is emitting a lot of warnings"

Now, the popup to add files to the interface
only shows supported files by default. It's of course
still possible to chose to show every possible files,
but it's not the default behaviour anymore.

a027c0b9 was a mistake.

It seems that Python is still sucking hard when it comes to encoding.

Namely, file-format specific ones