Merged in chrishamm's code queue and input buffer code
Increased heater tuning timeout for finding peak temperatire from 60 to
120 seconds
Implemented M204
Increased precision of reported coordinates to 3 decimal places
PanelDue status responses continue to be sent while executing
M109/116/190/191 commands
Temperatures now default to 0C instead of -273C
Handle G2 ande G3 in simulation mode
Implemented M586
Removed support for M557 P parameter. Use a bed.g file instead.