Feature request: caffeine taper / headache threshold

[RoyWiggins]

Keeping caffeine low enough for sleep is important, but for me my big difficulty is keeping it from dipping too low and triggering headaches, especially during attempts to taper. A second threshold which marks about how low a blood level I can tolerate before I get withdrawal would be quite useful.

For that matter, a way to mark headaches so you can estimate where that threshold is would also be useful.

Also, support for delay-release pills (see: Zest Caffeine).