Erlang `:observer` deps

Elixir is based on Erlang. Erlang has an thingie called :observer that spawns a GUI with running process. It’s very handy for debugging. But, on Arch it doesn’t work by default.

Install these packages and then recompile erlang to enable :observer and other UIs.

pacman -S fop libxslt wxwidgets-gtk3 glu mesa libpng unixodbc libssh ncurses webkit2gtk