This data corruption problem is very difficult. Just changing the code
a little bit changes whether the problem even happens and what is
affected. I need these changes in the main branch so I can operate with
the extra debug code always available and turned on.
Everything is setup such that if M100 is turned off or DEBUG(ECHO) is
turned off, the code is not affected. M100 has been made a little bit
more inteligent so it can display the serial command buffers in a more
meaningful way (because the data corruption seems to often times end up
in that area).
