- The new system has more hook points, and the method names are much more clear
now.
### Bidirectional communication for plugins
Formerly the `Kaleidoscope-Focus` plugin implemented a way for plugins to
register hooks that respond to commands sent from the host. A part of this has
been pulled into Kaleidoscope itself, in the form of the new `onFocusEvent`
hook. For most intents and purposes, this hook works similar to how focus hooks
worked previously, but has the advantage of not having to explicitly register
them: if you use a plugin that supports this feature, and you have the new
`Kaleidoscope-FocusSerial` plugin enabled, the commands will be made available.
This drastically simplifies both the plugins that wish to implement this, and the user sketches, which no longer need to explicitly register the focus hooks.
### Kaleidoscope.millisAtCycleStart()
Many plugins use timers, and most of them will call `millis()`, which isn't