Changes to the CubeCell libraries v1.4.0 and v1.5.0 required simpler interrupt handlers. Key Press handling is now done outside of IRQ context.
Ongoing problems with the CubeCell serial UART library was causing memory leaks on malloc/free with GPS port closure.
Here we include copies of the HardwareSerial code with fixes to avoid dynamic allocation.
When CubeCell updates the platform library to be useable, we can remove these.
Deep Sleep wake handling has been improved to sleep deeper (uA instead of mA) and wake on key input. Hopefully this has fewer GPS hangs as a result.