doc:more alternative packages and links
usr: add lightdm-gtk-greeter tweaks
usr: add startpage and duckduckgo as synapse search engines
usr: add ffmpegthubnailer as default thumbnailer for videos
usr: add xfce4-terminal colorschemes
usr: add gtksourceview-2.0 syntax highlighting files:
conkyrc.lang  dokuwiki.lang  markdown.lang  moinmoin.lang
usr: add gtksourceview color schemes
usr: add plymouth debian-logo theme
config, usr: add dconf default settings overrides
config, usr: add docf default settings overrides for gthumb
launchers: add abook.desktop
launchers: add gmail-mailto.desktop
launchers: add gpk-application.desktop
launchers: add mplayer.desktop
launchers: add mpsyt.desktop
launchers: add qiv.desktop
launchers: add ranger.desktop
launchers: add xclock.desktop
launchers: add xdg-file-manager.desktop
config, usr: add X11 config rule to enable touchpad vertical edge scrolling