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/Trigger.h

@@ -0,0 +1,54 @@
+/*----------------------------------------------------------------------------*/
+/* 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 <memory>
+#include <string>
+
+#include "SmartDashboard/Sendable.h"
+
+namespace frc {
+
+class Command;
+
+/**
+ * This class provides an easy way to link commands to inputs.
+ *
+ * It is very easy to link a polled input to a command.  For instance, you could
+ * link the trigger button of a joystick to a "score" command or an encoder
+ * reaching
+ * a particular value.
+ *
+ * It is encouraged that teams write a subclass of Trigger if they want to have
+ * something unusual (for instance, if they want to react to the user holding
+ * a button while the robot is reading a certain sensor input).  For this, they
+ * only have to write the {@link Trigger#Get()} method to get the full
+ * functionality
+ * of the Trigger class.
+ */
+class Trigger : public Sendable {
+ public:
+  Trigger() = default;
+  virtual ~Trigger() = default;
+  bool Grab();
+  virtual bool Get() = 0;
+  void WhenActive(Command* command);
+  void WhileActive(Command* command);
+  void WhenInactive(Command* command);
+  void CancelWhenActive(Command* command);
+  void ToggleWhenActive(Command* command);
+
+  void InitTable(std::shared_ptr<ITable> subtable) override;
+  std::shared_ptr<ITable> GetTable() const override;
+  std::string GetSmartDashboardType() const override;
+
+ protected:
+  std::shared_ptr<ITable> m_table;
+};
+
+}  // namespace frc