Update LiveWindow to provide continuous telemetry. (#771)

LiveWindow.updateValues() is now called from IterativeRobotBase on every
loop iteration.  Telemetry for all WPILib classes is enabled by default;
it can be disabled for specific classes using LiveWindow.disableTelemetry(),
or all telemetry can be disabled using LiveWindow.disableAllTelemetry().

This necessitated changing the hook methodology into other classes to
be more property-based rather than each class providing multiple functions.
This had the benefit of reducing boilerplate and increasing consistency.

- Remove NamedSendable, add name to Sendable.

- Provide SendableBase abstract class.

- Deprecate LiveWindow addSensor/addActuator interfaces.

- Add LiveWindow support to drive classes.

- Add addChild() helper functions to Subsystem.

- Fix inheritance hierarchy.  Now only sensors inherit from SensorBase.
  Other devices inherit from some combination of SendableBase, ErrorBase, or
  nothing.

wpilibc/src/main/native/include/ADXL362.h

@@ -7,26 +7,18 @@
 
 #pragma once
 
-#include <memory>
-#include <string>
-
-#include "LiveWindow/LiveWindowSendable.h"
 #include "SPI.h"
 #include "SensorBase.h"
 #include "interfaces/Accelerometer.h"
-#include "networktables/NetworkTableEntry.h"
 
 namespace frc {
 
-class DigitalInput;
-class DigitalOutput;
-
 /**
  * ADXL362 SPI Accelerometer.
  *
  * This class allows access to an Analog Devices ADXL362 3-axis accelerometer.
  */
-class ADXL362 : public Accelerometer, public LiveWindowSendable {
+class ADXL362 : public SensorBase, public Accelerometer {
  public:
   enum Axes { kAxis_X = 0x00, kAxis_Y = 0x02, kAxis_Z = 0x04 };
   struct AllAxes {
@@ -52,19 +44,11 @@ class ADXL362 : public Accelerometer, public LiveWindowSendable {
   virtual double GetAcceleration(Axes axis);
   virtual AllAxes GetAccelerations();
 
-  std::string GetSmartDashboardType() const override;
-  void InitTable(std::shared_ptr<nt::NetworkTable> subtable) override;
-  void UpdateTable() override;
-  void StartLiveWindowMode() override {}
-  void StopLiveWindowMode() override {}
+  void InitSendable(SendableBuilder& builder) override;
 
  private:
   SPI m_spi;
   double m_gsPerLSB = 0.001;
-
-  nt::NetworkTableEntry m_xEntry;
-  nt::NetworkTableEntry m_yEntry;
-  nt::NetworkTableEntry m_zEntry;
 };
 
 }  // namespace frc