Bangle.js 2 Cutting Edge - new heart rate algorithm

Ahh, ok - thanks for looking into it. It's because normally a custom file would communicate with the watch via the functions provided by lib/customize.js but you're including the Puck.js library directly and actually creating a new Bluetooth connection.

I added Puck.eval and .write to lib/customize.js a while back (and it's const Puck) so that must have messed it up. I'll see if there's a nice way to make to work or if we need to bodge it to use the Puck.js library again