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/AnalogInput.h

@@ -9,15 +9,10 @@
 
 #include <stdint.h>
 
-#include <memory>
-#include <string>
-
 #include <HAL/Types.h>
 
-#include "LiveWindow/LiveWindowSendable.h"
 #include "PIDSource.h"
 #include "SensorBase.h"
-#include "networktables/NetworkTableEntry.h"
 
 namespace frc {
 
@@ -33,9 +28,7 @@ namespace frc {
  * are divided by the number of samples to retain the resolution, but get more
  * stable values.
  */
-class AnalogInput : public SensorBase,
-                    public PIDSource,
-                    public LiveWindowSendable {
+class AnalogInput : public SensorBase, public PIDSource {
   friend class AnalogTrigger;
   friend class AnalogGyro;
 
@@ -45,7 +38,7 @@ class AnalogInput : public SensorBase,
   static constexpr int kAccumulatorChannels[kAccumulatorNumChannels] = {0, 1};
 
   explicit AnalogInput(int channel);
-  virtual ~AnalogInput();
+  ~AnalogInput() override;
 
   int GetValue() const;
   int GetAverageValue() const;
@@ -78,19 +71,13 @@ class AnalogInput : public SensorBase,
 
   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:
   int m_channel;
   // TODO: Adjust HAL to avoid use of raw pointers.
   HAL_AnalogInputHandle m_port;
   int64_t m_accumulatorOffset;
-
-  nt::NetworkTableEntry m_valueEntry;
 };
 
 }  // namespace frc