...seems like a more lightweight way of providing various settings to
Gtk apps (and maybe other stuff? I'm not sure).

Various other font tweaks and such in this commit.

- messes with DPI & fonts
- changes trayer height
- rewrites chunks of xmonad.hs to use EZConfig style bindings, rofi for
  launcher and i3lock for a lock screen (thanks @benlemasurier), and a
  slightly different set of layouts.  also handles some fancy laptop keys
  like volume adjustment.  still need to steal casey & tyler's stuffs for
  backlight handling, probably.

for now, i'm going to keep these changes in a separate branch rather than
attempt to make them work on all of my systems.  I'm running Debian Stretch
on here and the monitor is giant, so it would likely be a hassle, and it's
small enough that i can probably just manage as a separate branch as long
as needed.

Getting old may beat the alternatives, but it sure is kind of shit on its
own terms in a lot of ways.