emacs: switch to semester 2
i3/status: force i3bar json output
i3/status: switch to i3blocks.

i3blocks is significantly more powerful (albeit more insane) than
i3status is at generating output.  for that reason, this switch lets us
do awesome stuff like custom blocks and triggers.
i3: add terminals space.
zsh: add nanoc completion
i3: general configuration bumping
wallpapers: update walls list
emacs: add org-tree-slide.