C++ Shuffleboard fixes (#1595)

* Fix C++ ShuffleboardComponent template type

* Fix `WithWidget(WidgetType&)`not being properly capitalized

* Fix data members across dll boundaries by using enum for built in types

wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardWidget.cpp

@@ -0,0 +1,41 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. 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 the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "frc/shuffleboard/ShuffleboardWidget.h"
+
+using namespace frc;
+
+static constexpr const char* widgetStrings[] = {
+    "Text View",
+    "Number Slider",
+    "Number Bar",
+    "Simple Dial",
+    "Graph",
+    "Boolean Box",
+    "Toggle Button",
+    "Toggle Switch",
+    "Voltage View",
+    "PDP",
+    "ComboBox Chooser",
+    "Split Button Chooser",
+    "Encoder",
+    "Speed Controller",
+    "Command",
+    "PID Command",
+    "PID Controller",
+    "Accelerometer",
+    "3-Axis Accelerometer",
+    "Gyro",
+    "Relay",
+    "Differential Drivebase",
+    "Mecanum Drivebase",
+    "Camera Stream",
+};
+
+const char* detail::GetStringForWidgetType(BuiltInWidgets type) {
+  return widgetStrings[static_cast<int>(type)];
+}