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/cpp/AnalogOutput.cpp

@@ -14,7 +14,8 @@
 #include <llvm/SmallString.h>
 #include <llvm/raw_ostream.h>
 
-#include "LiveWindow/LiveWindow.h"
+#include "SensorBase.h"
+#include "SmartDashboard/SendableBuilder.h"
 #include "WPIErrors.h"
 
 using namespace frc;
@@ -51,8 +52,8 @@ AnalogOutput::AnalogOutput(int channel) {
     return;
   }
 
-  LiveWindow::GetInstance()->AddActuator("AnalogOutput", m_channel, this);
   HAL_Report(HALUsageReporting::kResourceType_AnalogOutput, m_channel);
+  SetName("AnalogOutput", m_channel);
 }
 
 /**
@@ -93,23 +94,8 @@ double AnalogOutput::GetVoltage() const {
   return voltage;
 }
 
-void AnalogOutput::UpdateTable() {
-  if (m_valueEntry) m_valueEntry.SetDouble(GetVoltage());
-}
-
-void AnalogOutput::StartLiveWindowMode() {}
-
-void AnalogOutput::StopLiveWindowMode() {}
-
-std::string AnalogOutput::GetSmartDashboardType() const {
-  return "Analog Output";
-}
-
-void AnalogOutput::InitTable(std::shared_ptr<nt::NetworkTable> subTable) {
-  if (subTable) {
-    m_valueEntry = subTable->GetEntry("Value");
-    UpdateTable();
-  } else {
-    m_valueEntry = nt::NetworkTableEntry();
-  }
+void AnalogOutput::InitSendable(SendableBuilder& builder) {
+  builder.SetSmartDashboardType("Analog Output");
+  builder.AddDoubleProperty("Value", [=]() { return GetVoltage(); },
+                            [=](double value) { SetVoltage(value); });
 }