[core] Rework core implementation

Experimental re-implementation of core functionality with the aim:
- Depend only on the Python Standard Library for core
- If modules are missing elsewhere, *never* throw
- Unit test *everything*
- Cleaner and more minimal implementation
- Better integration points for existing implementations (charts,
  braille, etc.)
- Full backwards-compatibility with existing module system (except where
  modules can be vastly simplified)

bin/toggle-display.sh

@@ -1,15 +0,0 @@
-#!/usr/bin/env bash
-
-echo $(dirname $(readlink -f "$0"))
-
-i3bar_update=$(dirname $(readlink -f "$0"))/load-i3-bars.sh
-
-xrandr "$@"
-
-if [ -f $i3bar_update ]; then
-	sleep 1
-	if [ -f ~/.config/i3/images/background.png ]; then
-		feh --bg-fill ~/.config/i3/images/background.png
-	fi
-	$i3bar_update
-fi