Added an Accelerometer interface

ADXL345_I2C, ADXL345_SPI, and BuiltInAccelerometer implement this interface.

The analog accelerometer class Accelerometer was renamed to
AnalogAccelerometer.

Change-Id: Iaae79d582a24c36c372f5fd4ea6df37be289b9c1

wpilibc/wpilibC++/include/AnalogAccelerometer.h

@@ -0,0 +1,46 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008. All Rights Reserved.							  */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in $(WIND_BASE)/WPILib.  */
+/*----------------------------------------------------------------------------*/
+#pragma once
+
+#include "AnalogInput.h"
+#include "SensorBase.h"
+#include "PIDSource.h"
+#include "LiveWindow/LiveWindowSendable.h"
+
+/**
+ * Handle operation of an analog accelerometer.
+ * The accelerometer reads acceleration directly through the sensor. Many sensors have
+ * multiple axis and can be treated as multiple devices. Each is calibrated by finding
+ * the center value over a period of time.
+ */
+class AnalogAccelerometer : public SensorBase, public PIDSource, public LiveWindowSendable {
+public:
+	explicit AnalogAccelerometer(uint32_t channel);
+	explicit AnalogAccelerometer(AnalogInput *channel);
+	virtual ~AnalogAccelerometer();
+
+	float GetAcceleration();
+	void SetSensitivity(float sensitivity);
+	void SetZero(float zero);
+	double PIDGet();
+
+	void UpdateTable();
+	void StartLiveWindowMode();
+	void StopLiveWindowMode();
+	std::string GetSmartDashboardType();
+	void InitTable(ITable *subTable);
+	ITable * GetTable();
+
+private:
+	void InitAccelerometer();
+
+	AnalogInput *m_AnalogInput;
+	float m_voltsPerG;
+	float m_zeroGVoltage;
+	bool m_allocatedChannel;
+
+	ITable *m_table;
+};