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/Buttons/Button.h

@@ -0,0 +1,36 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2011-2017. 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
+
+#include "Buttons/Trigger.h"
+#include "Commands/Command.h"
+
+namespace frc {
+
+/**
+ * This class provides an easy way to link commands to OI inputs.
+ *
+ * It is very easy to link a button to a command.  For instance, you could
+ * link the trigger button of a joystick to a "score" command.
+ *
+ * This class represents a subclass of Trigger that is specifically aimed at
+ * buttons on an operator interface as a common use case of the more generalized
+ * Trigger objects. This is a simple wrapper around Trigger with the method
+ * names
+ * renamed to fit the Button object use.
+ */
+class Button : public Trigger {
+ public:
+  virtual void WhenPressed(Command* command);
+  virtual void WhileHeld(Command* command);
+  virtual void WhenReleased(Command* command);
+  virtual void CancelWhenPressed(Command* command);
+  virtual void ToggleWhenPressed(Command* command);
+};
+
+}  // namespace frc