Like all of the BBTools suite (BBWeather, BBCorrector, etc.), BBLight was written by Chris Miles atleast 3 or 4 years ago and released as Open Source software.

Because of this forum thread of yours, I rearranged the options menu, added the SMS and email monitoring functionality and changed the way the "Out of Holster" and "External Power" options work. In fact, the "Out of Holster" and "External Power" options never worked for me, so that is why I changed them.

Installing over the old version should work fine, it did for me. You might be forced to do a reboot after uninstalling it anyway.

I'm not sure about disabling PocketDay but it would make sense to disable it while testing BBLight, you would never know which app was actually controlling the backlight.