Fixed error with z-homing in previous release

Fixed a random hang after z-homing in the previous release. Also make Z
probe temperature coefficient default to zero always, and Z probe
calibration temperature default to current bed temperature always.

Configuration.h

@@ -24,7 +24,7 @@ Licence: GPL
 #define CONFIGURATION_H
 
 #define NAME "RepRapFirmware"
-#define VERSION "0.57o-dc42"
+#define VERSION "0.57p-dc42"
 #define DATE "2014-02-24"
 #define LAST_AUTHOR "dc42"
 

GCodes.cpp

@@ -923,7 +923,7 @@ bool GCodes::SetPrintZProbe(GCodeBuffer* gb, char* reply)
 		{
 			params.calibTemperature = gb->GetFValue();
 		}
-		else if (!PrintingAFile())
+		else
 		{
 			// Use the current bed temperature as the calibration temperature if no value was provided
 			params.calibTemperature = platform->GetTemperature(0);
@@ -932,6 +932,10 @@ bool GCodes::SetPrintZProbe(GCodeBuffer* gb, char* reply)
 		{
 			params.temperatureCoefficient = gb->GetFValue();
 		}
+		else
+		{
+			params.temperatureCoefficient = 0.0;
+		}
 		platform->SetZProbeParameters(params);
 	}
 	else

Move.h

@@ -564,7 +564,7 @@ inline void Move::HitLowStop(int8_t drive, LookAhead* la, DDA* hitDDA)
 		{
 			// Executing G30, so set the current Z height to the value at which the end stop is triggered
 			// Transform it first so that the height is correct in user coordinates
-			float xyzPoint[3];
+			float xyzPoint[DRIVES + 1];
 			LiveCoordinates(xyzPoint);
 			xyzPoint[Z_AXIS] = lastZHit = platform->ZProbeStopHeight();
 			Transform(xyzPoint);

Platform.cpp

@@ -86,8 +86,8 @@ void Platform::Init()
 	  nvData.gateWay = GATE_WAY;
 
 	  nvData.zProbeType = 0;	// Default is to use the switch
-	  nvData.irZProbeParameters.Init(false);
+	  nvData.irZProbeParameters.Init();
-	  nvData.ultrasonicZProbeParameters.Init(true);
+	  nvData.ultrasonicZProbeParameters.Init();
 
 	  nvData.magic = FlashData::magicValue;
   }

Platform.h

@@ -420,14 +420,12 @@ struct ZProbeParameters
 	float calibTemperature;			// the temperature at which we did the calibration
 	float temperatureCoefficient;	// the variation of height with bed temperature
 
-	void Init(bool isUltrasonic)
+	void Init()
 	{
 		adcValue = Z_PROBE_AD_VALUE;
 		height = Z_PROBE_STOP_HEIGHT;
 		calibTemperature = 20.0;
-		temperatureCoefficient = (isUltrasonic)
+		temperatureCoefficient = 0.0;	// no default temperature correction
-									? 0.007575		// speed of sound correction assuming half wavelength between sensor and bed
-									: 0.0;			// no default temperature correction for IR sensor
 	}
 
 	float GetStopHeight(float temperature) const