Improve command line interface

[osresearch]

The write-ram tool is a bit of a hack and could be merged into a read/write/monitor tool. The command protocol should be updated to include ACKs and ensure that the serial port is in the correct mode.

[osresearch]

Proposal for the spispy command line utility:

Usage:
  -h | --help                    This help
  -d | --device /dev/ttyACM0     Serial port device
  -b | --baud 3000000            Baud rate (for FTDI serial)

  -r | --read file               Read RAM into file
  -w | --write file              Write RAM from file
  -R | --read-flash file         Read flash into file
  -W | --write-flash file        Write flash from file
  -a | --address 0x0             RAM/flash address to read from
  -l | --length 0x1000           Length to read from RAM/flash
  -z | --size 16                 Flash chip size in MiB
  -c | --clone                   Clone the flash chip into RAM

  -i | --id cf2316               Set flash chip ID in RAM
  -I | --flash-id                Read the flash chip ID from flash

  -s | --sfdp file               Write RAM SFDP from file
  -S | --sfdp-flash file         Read flash SFDP into file

  -m | --monitor                 Monitor flash access patterns
  -e | --emulate                 Enable flash emulation mode
  -n | --no-emulate              Turn off flash emulation mode

  -t | --toctou                  Need to figure out how this works