Bookends v4.0.1

Compatibility fix: Bookends' internal modules used generic names (config.lua, utils.lua, etc.) that could collide with similarly-named modules in other plugins and stop them from loading. All internals are now prefixed with bookends_ so nothing else gets clobbered.

Confirmed fix for Customisable Sleep Screen. Safe to install over v4.0.0; no user-visible changes.