Kangaroo firmware freezes in standby mode

At least one Kangaroo board is freezing when in standby mode.

This was observed on the bench, with the board not having sent a message for over a day and the last log message saying it was going into standby mode. Pressing the test button did not wake the board up, meaning the external interrupt connected to the button was not recognised.

A possible fix is to stop the on chip voltage regulator going to low power mode when the MCU goes into standby mode.