[Cryptech Tech] Status tamper detection and MKM erasure

[Linus Nordberg]

Hi,

The code in https://trac.cryptech.is/browser/user/ln5/tamper, running on
the AVR, successfully detects panic button being pressed and reads and
writes the master key memory on the alpha board.

Next up is lowering power consumption in idle mode (disable unused
functions, use interrupts instead of busy-looping) and speed up erasure
(write in "sequential mode") and implementing some kind of POST function
in collaboration with the FPGA and the ARM.

Code review and other comments most welcome!