Update MultiExtColorMix.py

Add functionality for 4-in-one-out hot ends.
Add an exit if the firmware is RepRap (M567 is not supported).

Update MultiExtColorMix.py

Change the variable names to start with lower case letter.  Altered messages to include a title.

Update MultiExtColorMix.py

More variable name changes.  Changed some string formats to templates.

Update MultiExtColorMix.py

merge 2