Add gear range arguments to AnalogShifter

This allows for limiting the shifter range, say if you want to build a 5-speed analog shifter.

More importantly it allows us to put the shifter in reverse without having to define a pin to read the reverse signal from.

Author: dmadison

src/SimRacing.cpp

@@ -692,12 +692,12 @@ const float AnalogShifter::CalEngagementPoint = 0.70;
 const float AnalogShifter::CalReleasePoint = 0.50;
 const float AnalogShifter::CalEdgeOffset = 0.60;
 
-AnalogShifter::AnalogShifter(PinNum pinX, PinNum pinY, PinNum pinRev, PinNum detectPin, bool detectActiveLow)
-	: 
-	/* In initializing the Shifter, the lowest gear is going to be '-1' if a pin
-	* exists for reverse, otherwise it's going to be '0' (neutral).
-	*/
-	Shifter(sanitizePin(pinRev) != UnusedPin ? -1 : 0, 6),
+AnalogShifter::AnalogShifter(
+	Gear gearMin, Gear gearMax,
+	PinNum pinX, PinNum pinY, PinNum pinRev,
+	PinNum detectPin, bool detectActiveLow
+) : 
+	Shifter(gearMin, gearMax),
 
 	/* Two axes, X and Y */
 	analogAxis{ AnalogInput(pinX), AnalogInput(pinY) },
@@ -1014,6 +1014,7 @@ void AnalogShifter::serialCalibration(Stream& iface) {
 
 LogitechShifter::LogitechShifter(PinNum pinX, PinNum pinY, PinNum pinRev, PinNum detectPin)
 	: AnalogShifter(
+		-1, 6,  // includes reverse and gears 1-6
 		pinX, pinY, pinRev, 
 		detectPin, false  // active high
 	)

src/SimRacing.h

@@ -582,14 +582,23 @@ namespace SimRacing {
 		/**
 		* Class constructor
 		* 
+		* @param gearMin         the lowest gear possible
+		* @param gearMax         the highest gear possible
 		* @param pinX            the analog input pin for the X axis
 		* @param pinY            the analog input pin for the Y axis
 		* @param pinRev          the digital input pin for the 'reverse' button
 		* @param pinDetect       the digital pin for device detection
-		* @param detectActiveLow whether the device is detected on a high signal (false,
-		*                        default) or a low signal (true)
+		* @param detectActiveLow whether the device is detected on a high signal
+		*                         (false, default) or a low signal (true)
+		* 
+		* @note With the way the class is designed, the lowest possible gear is
+		*       -1 (reverse), and the highest possible gear is 6. Setting the
+		*       arguments lower/higher than this will have no effect. Setting
+		*       the arguments within this range will limit to those gears,
+		*       and selecting gears out of range will result in neutral.
 		*/
 		AnalogShifter(
+			Gear gearMin, Gear gearMax,
 			PinNum pinX, PinNum pinY,
 			PinNum pinRev = UnusedPin,
 			PinNum pinDetect = UnusedPin, bool detectActiveLow = false