Move CameraServer and WPILib headers into their own folder

The old headers were moved into folders because doing so avoids polluting
the system include directories.

Folder names were also normalized to lowercase.

hal/src/test/native/cpp/sim/AccelerometerSimTest.cpp

@@ -0,0 +1,42 @@
+/*----------------------------------------------------------------------------*/
+/* 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 "gtest/gtest.h"
+#include "hal/Accelerometer.h"
+#include "hal/HAL.h"
+#include "simulation/AccelerometerSim.h"
+
+using namespace frc::sim;
+
+namespace hal {
+
+TEST(AcclerometerSimTests, TestActiveCallback) {
+  HAL_Initialize(500, 0);
+
+  AccelerometerSim sim{0};
+
+  sim.ResetData();
+
+  bool wasTriggered = false;
+  bool lastValue = false;
+
+  auto cb = sim.RegisterActiveCallback(
+      [&](wpi::StringRef name, const HAL_Value* value) {
+        wasTriggered = true;
+        lastValue = value->data.v_boolean;
+      },
+      false);
+
+  EXPECT_FALSE(wasTriggered);
+
+  HAL_SetAccelerometerActive(true);
+
+  EXPECT_TRUE(wasTriggered);
+  EXPECT_TRUE(lastValue);
+}
+
+}  // namespace hal