Fix reversed logic for output shifter (#308)

* add reversed output logic

* missed reversed output logic for clear()

* using MF_LOW and MF_HIGH like for the outputs

* fic reversed logic for output shifter

src/MF_OutputShifter/MFOutputShifter.h

@@ -8,7 +8,7 @@
 
 #include <Arduino.h>
 
-#ifdef REVERSED_OUTPUT_OUTPUT
+#ifdef REVERSED_OUTPUT_OUTPUTSHIFTER
     #define MF_HIGH LOW
     #define MF_LOW  HIGH
 #else