Manjaro - Are these "orphaned" packages safe to remove?

Hi.

Manjaro with Gnome. I'm not sure if theese packages are safe to remove.
pacman -Qdt gives me:

autogen 5.18.7-1
bamf 0.5.1-1
bzr 2.7.0-1
clutter-gst2 2.0.16-1
gnome-common 3.18.0-1
lib32-gconf 3.2.6-1
lib32-glew1.10 1.10.0-2
lib32-libappindicator-gtk2 12.10.0-6
lib32-libgcrypt15 1.5.3-2
lib32-libjpeg6-turbo 1.4.2-1
lib32-libnm-glib46 0.9.8.10-1
lib32-libpng12 1.2.53-2
lib32-libudev0 182-1
lib32-libvpx 1.5.0-1
lib32-sdl_ttf 2.0.11-3
libanjuta 3.18.2-3
libappindicator-gtk2 12.10.0-5
libdbusmenu-gtk3 16.04.0-1
libgda 5.2.4-2
libunity 7.1.4-2
libvncserver 0.9.10-4
python-pyqt4 4.11.4-4
python2-gconf 2.28.1-9
python2-keybinder2 0.3.0-2
python2-pillow 3.1.1-1
python2-wnck 2.32.0-15
python2-xdg 0.25-3
python2-xlib 0.15rc1-7
splix 2.0.0-13
telepathy-farstream 0.6.2-2

pacman -Rsn (pacman -Qqdt) expands that list with dependencies to:

autoconf-archive-1:2015.09.25-1
dee-1.2.7-6
docbook-xml-4.5-6
docbook-xsl-1.79.1-1
farstream-0.2.7-1
gdl-3.18.0-1
goocanvas-2.0.2-1
graphviz-2.38.0-11
gtk-doc-1.24-1
gts-0.7.6-3
intltool-0.51.0-1
itstool-2.0.2-1
lib32-at-spi2-atk-2.18.1-1
lib32-at-spi2-core-2.18.3-1
lib32-atk-2.18.0-1
lib32-cairo-1.14.6-2
lib32-colord-1.2.12-1
lib32-cracklib-2.9.4-1
lib32-dbus-glib-0.104-1
lib32-dconf-0.24.0-1
lib32-e2fsprogs-1.42.13-1
lib32-gdk-pixbuf2-2.32.3-1
lib32-glib-networking-2.46.1-1
lib32-gtk2-2.24.30-1
lib32-gtk3-3.18.9-1
lib32-js17-17.0.0-5
lib32-json-glib-1.0.4-1
lib32-keyutils-1.5.9-1
lib32-krb5-1.13.2-3
lib32-libcroco-0.6.11-1
lib32-libcups-2.1.3-1
lib32-libdatrie-0.2.10-1
lib32-libdbusmenu-glib-16.04.0-1
lib32-libdbusmenu-gtk2-16.04.0-1
lib32-libepoxy-1.3.1-3
lib32-libgudev-230-1
lib32-libgusb-0.2.8-1
lib32-libindicator-gtk2-12.10.1-7
lib32-libldap-2.4.43-2
lib32-libproxy-0.4.12-1
lib32-librsvg-2.40.13-1
lib32-libsoup-2.52.2-1
lib32-libthai-0.1.24-1
lib32-libtirpc-1.0.1-1
lib32-libxcomposite-0.4.4-2
lib32-libxft-2.3.2-1
lib32-libxinerama-1.1.3-1
lib32-libxkbcommon-0.5.0-1
lib32-nspr-4.12-1
lib32-nss-3.22.1-1
lib32-pam-1.2.1-2
lib32-pango-1.39.0-1
lib32-pixman-0.34.0-1
lib32-polkit-0.113-2
lib32-rest-0.7.93-1
libdbusmenu-glib-16.04.0-1
libdbusmenu-gtk2-16.04.0-1
libkeybinder2-0.3.0-2
libnice-0.1.13-1
perl-xml-parser-2.44-2
pyqt4-common-4.11.4-4
python-sip-4.17-1
sdl_ttf-2.0.11-3
sip-4.17-1
source-highlight-3.1.8-6
yelp-tools-3.18.0-1
autogen-5.18.7-1
bamf-0.5.1-1
bzr-2.7.0-1
clutter-gst2-2.0.16-1
gnome-common-3.18.0-1
lib32-gconf-3.2.6-1
lib32-glew1.10-1.10.0-2
lib32-libappindicator-gtk2-12.10.0-6
lib32-libgcrypt15-1.5.3-2
lib32-libjpeg6-turbo-1.4.2-1
lib32-libnm-glib46-0.9.8.10-1
lib32-libpng12-1.2.53-2
lib32-libudev0-182-1
lib32-libvpx-1.5.0-1
lib32-sdl_ttf-2.0.11-3
libanjuta-3.18.2-3
libappindicator-gtk2-12.10.0-5
libdbusmenu-gtk3-16.04.0-1
libgda-5.2.4-2
libunity-7.1.4-2
libvncserver-0.9.10-4
python-pyqt4-4.11.4-4
python2-gconf-2.28.1-9
python2-keybinder2-0.3.0-2
python2-pillow-3.1.1-1
python2-wnck-2.32.0-15
python2-xdg-0.25-3
python2-xlib-0.15rc1-7
splix-2.0.0-13
telepathy-farstream-0.6.2-2

I've checked pacman -Qdt packages, and they seem don't seem to be used by anything else, nor do I use them (I think, I might be wrong).
Is it safe to assume that the big list is also safe to remove?

Usually, its safe.
One package that catched my attention is gnome-common.
Check its dependencies to be sure (https://www.archlinux.org/packages/extra/any/gnome-common/).

Wich packages it gives you with 'pacman -Qdttq'?

Thanks for your reply!

pacman -Qdttq gives me this:

autogen
bamf
bzr
clutter-gst2
gnome-common
grantlee-qt4
lib32-gconf
lib32-glew1.10
lib32-libappindicator-gtk2
lib32-libgcrypt15
lib32-libjpeg6-turbo
lib32-libnm-glib46
lib32-libpng12
lib32-libudev0
lib32-libvpx
lib32-sdl_ttf
libanjuta
libappindicator-gtk2
libdbusmenu-gtk3
libgda
libunity
libvncserver
python-pyqt4
python2-gconf
python2-keybinder2
python2-pillow
python2-wnck
python2-xdg
python2-xlib
splix
telepathy-farstream

What does the second "t" do?
Also, on my system I have some packages that are listed on the link you've given me (under "required by"), but they don't list gnome-common as a dependency. Which should I trust?

Finally, assuming that all the orphans are, in fact, unused, is it ok to conclude that all 96 packages that pacman -Rsn wants to remove are also safe to remove?

Orphaned Packages (for future reference) is any package that is not being used by the System itself and serve no purpose. so yes you can remove them you won't have a problem.

As for what does t do in BASH.

if you type in pacman -Qh for Query options

it should tell you what each letter command does. t in your case is to do a dependancy test.