fix(sleep): Put BHI, BME and ECG into standby

When going to sleep while e.g. running "G-Watch", the BHI continued to run, drawing about 1 mA. This drained the battery.

Fix is to turn all sensors off before going to sleep.

changed milestone to %v1.15

Looks good to me! Thanks for keeping our codebase clean.

However, I'm only a bot - so a human will still have to approve this request.

merged

mentioned in commit 8115a86f

We should consider adding another central function for disabling all peripherals, similar to hardware_init for initialization.