Small rewrite to make a much clearer state-machine

The previous reinitialization-code has some weird behavior in that it
sends two extra 0x55 back after the start-byte has been received. For
proper debugging it was needed to write the code much clearer. And maybe
remove the bug that way as well.
Small rewrite to make a much clearer state-machine

The previous reinitialization-code has some weird behavior in that it
sends two extra 0x55 back after the start-byte has been received. For
proper debugging it was needed to write the code much clearer. And maybe
remove the bug that way as well.
Payload length doesn't need to be odd anymore

Now that we detect several wrong command-codes (0x00, 0x55, 0xFE, 0xFF)
it is no longer needed to have odd parity.
Merge branch 'master' of github.com:michielbrink/quadcopter