Major new 2019 upgrades for S4.

1. Major processor upgrade to the ARM Cortex M4 thru the Adafruit ItsyBitsy M4 Express.   
2. The new processor allows a major change in form factor to the PocketQube 1p - a 50% decrease in volume.
3. The new processor allows a major change in form factor to PocketQube standard stacked 42mm square PCBs with a common bus for power and communications.
4. Communications have been simplified to LoRa.
5. Performance improved by ~4x.
6. Mission memory simplified to totally solid state flash removing occasional memory loss due to flight stress on uSD cards in mechanical carriers.   Major increase in reliability.
7. New sensors for atmospheric aerosols spectroscopy, light spectroscopy, UV light, IR imaging.
8. New I2C GPS with new altitude limit of ~80 km.