Various cleanups ahead of digipot save

Marlin/Makefile

@@ -290,8 +290,8 @@ ifeq ($(HARDWARE_VARIANT), Teensy)
 SRC = wiring.c
 VPATH += $(ARDUINO_INSTALL_DIR)/hardware/teensy/cores/teensy
 endif
-CXXSRC = WMath.cpp WString.cpp Print.cpp Marlin_main.cpp	\
-	MarlinSerial.cpp Sd2Card.cpp SdBaseFile.cpp SdFatUtil.cpp	\
+CXXSRC = WMath.cpp WString.cpp Print.cpp Marlin_main.cpp \
+	MarlinSerial.cpp Sd2Card.cpp SdBaseFile.cpp SdFatUtil.cpp \
 	SdFile.cpp SdVolume.cpp planner.cpp stepper.cpp \
 	temperature.cpp cardreader.cpp configuration_store.cpp \
 	watchdog.cpp SPI.cpp servo.cpp Tone.cpp ultralcd.cpp digipot_mcp4451.cpp \