[Add a functionality] Add a privacy mode

[FR. Loïc]

Hi,

Thank you for your work.
It would be very interesting to have a privacy mode that:
_disable research in pluma (Bleachbit can not even do that ...)
_Disable recent file (GTK2, GTK3, KDE)
_Disable backup of preview image files

So have a "Privacy Mode" button in "MATE Tweak" that will do this:
# GTK2
echo "gtk-recent-files-max-age=0" >> ~/.gtkrc-2.0

# GTK3
mkdir -p ~/.config/gtk-3.0
echo -e "[Settings]\ngtk-recent-files-max-age=0\ngtk-recent-files-limit=0" > ~/.config/gtk-3.0/settings.ini
rm ~/.local/share/recently-used.xbel

# KDE
chmod -w ~/.kde/share/apps/RecentDocuments/

# TMP or TMPFS
ln -s /tmp ~/.thumbnails
ln -s /tmp ~/.cache/thumbnails

Thanks !