Update to 2018_v4 image and new build system. (#598)

* Revert "Force OpenCV to 3.1.0 (#602)"

This reverts commit 50ed55e8e2.

* Removes Simulation

* Removes old build system

* Removes old gtest

* Adds new gmock and gtest

* Updates to new ni-libraries

* removes MyRobot (to be replaced)

* moves files to new location

* Adds new sim backend and new test executables

* updates .styleguide and .gitignore

* Changes cpp WPILibVersion to a function

MSVC throws an AV with the old version.

* Disables USBCamera on all systems except for linux

* 2018 NI Libraries

* New build system

wpilibc/src/main/native/include/interfaces/Gyro.h

@@ -0,0 +1,60 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2014-2017. 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+namespace frc {
+
+/**
+ * Interface for yaw rate gyros
+ */
+class Gyro {
+ public:
+  virtual ~Gyro() = default;
+
+  /**
+   * Calibrate the gyro by running for a number of samples and computing the
+   * center value. Then use the center value as the Accumulator center value for
+   * subsequent measurements. It's important to make sure that the robot is not
+   * moving while the centering calculations are in progress, this is typically
+   * done when the robot is first turned on while it's sitting at rest before
+   * the competition starts.
+   */
+  virtual void Calibrate() = 0;
+
+  /**
+   * Reset the gyro. Resets the gyro to a heading of zero. This can be used if
+   * there is significant drift in the gyro and it needs to be recalibrated
+   * after it has been running.
+   */
+  virtual void Reset() = 0;
+
+  /**
+   * Return the actual angle in degrees that the robot is currently facing.
+   *
+   * The angle is based on the current accumulator value corrected by the
+   * oversampling rate, the gyro type and the A/D calibration values. The angle
+   * is continuous, that is it will continue from 360 to 361 degrees. This
+   * allows algorithms that wouldn't want to see a discontinuity in the gyro
+   * output as it sweeps past from 360 to 0 on the second time around.
+   *
+   * @return the current heading of the robot in degrees. This heading is based
+   *         on integration of the returned rate from the gyro.
+   */
+  virtual double GetAngle() const = 0;
+
+  /**
+   * Return the rate of rotation of the gyro
+   *
+   * The rate is based on the most recent reading of the gyro analog value
+   *
+   * @return the current rate in degrees per second
+   */
+  virtual double GetRate() const = 0;
+};
+
+}  // namespace frc