Results 3 issues of alchemyEngine

Update the M141 gcode_macro, removing invalid default_parameter parameters as per #137

Addresses two minor issues around start-up temperature handling: - Initial 0.0degC "reading" no longer affects smoothing and adjustment on start up - Fixes min_temp reporting for front-end client: no longer...

reviewer needed

Using ['configfile']['settings'] returns all defaults, therefore there is always a ['gear_ratio'] key. Check for empty list instead of checking for the key.