Initial version of CM3SD serial flash loader
Fix bug in parsing objdump hex files
Handle bogus input better, if the chip is just blasting it before reset
Wait a bit before reset if the programming happened too fast.

Otherwise the user might still be holding the BOOT button, triggering
a re-entry of the bootloader after reset.
Reopen the serial port occasionally while trying to connect to bootloader
Remove spurious sleep
Fix checksum calculation
Remove spurious debug print
Only initialize bootloader when it's needed
Check bootloader response text
Add README
Workaround possible baudrate bug