persistent hooks (inhibit shutdown)

If anybody's interested, I've been playing around with more complex hook setups and wrote a hook/script to track the pacman process during transactions and inhibit shutdown.[0] This technique could be used for hooks with pre and post transaction components that need need tighter coupling than separate hooks allow or to setup post transaction hooks that are guaranteed to run even if the transaction fails, unlike our current implementation of PostTransaction hooks. [0]: https://github.com/andrewgregory/pachooks/blob/a15e08d7321f17aae2431bddc1e9b...