[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/pacman-updates

@@ -1,22 +0,0 @@
-#!/usr/bin/bash
-
-if ! type -P fakeroot >/dev/null; then
-	error 'Cannot find the fakeroot binary.'
-	exit 1
-fi
-
-if [[ -z $CHECKUPDATES_DB ]]; then
-	CHECKUPDATES_DB="${TMPDIR:-/tmp}/checkup-db-${USER}/"
-fi
-
-trap 'rm -f $CHECKUPDATES_DB/db.lck' INT TERM EXIT
-
-DBPath="${DBPath:-/var/lib/pacman/}"
-eval $(awk -F' *= *' '$1 ~ /DBPath/ { print $1 "=" $2 }' /etc/pacman.conf)
-
-mkdir -p "$CHECKUPDATES_DB"
-ln -s "${DBPath}/local" "$CHECKUPDATES_DB" &> /dev/null
-fakeroot -- pacman -Sy --dbpath "$CHECKUPDATES_DB" --logfile /dev/null &> /dev/null
-fakeroot pacman -Su -p --dbpath "$CHECKUPDATES_DB"
-
-exit 0