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/AnalogAccelerometer.h

@@ -8,13 +8,10 @@
 #pragma once
 
 #include <memory>
-#include <string>
 
 #include "AnalogInput.h"
-#include "LiveWindow/LiveWindowSendable.h"
 #include "PIDSource.h"
 #include "SensorBase.h"
-#include "networktables/NetworkTableEntry.h"
 
 namespace frc {
 
@@ -25,25 +22,19 @@ namespace frc {
  * 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 {
+class AnalogAccelerometer : public SensorBase, public PIDSource {
  public:
   explicit AnalogAccelerometer(int channel);
   explicit AnalogAccelerometer(AnalogInput* channel);
   explicit AnalogAccelerometer(std::shared_ptr<AnalogInput> channel);
-  virtual ~AnalogAccelerometer() = default;
+  ~AnalogAccelerometer() override = default;
 
   double GetAcceleration() const;
   void SetSensitivity(double sensitivity);
   void SetZero(double zero);
   double PIDGet() override;
 
-  void UpdateTable() override;
-  void StartLiveWindowMode() override;
-  void StopLiveWindowMode() override;
-  std::string GetSmartDashboardType() const override;
-  void InitTable(std::shared_ptr<nt::NetworkTable> subTable) override;
+  void InitSendable(SendableBuilder& builder) override;
 
  private:
   void InitAccelerometer();
@@ -51,8 +42,6 @@ class AnalogAccelerometer : public SensorBase,
   std::shared_ptr<AnalogInput> m_analogInput;
   double m_voltsPerG = 1.0;
   double m_zeroGVoltage = 2.5;
-
-  nt::NetworkTableEntry m_valueEntry;
 };
 
 }  // namespace frc