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/DigitalSource.h

@@ -0,0 +1,34 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008-2017. 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 "HAL/Types.h"
+#include "InterruptableSensorBase.h"
+
+namespace frc {
+
+/**
+ * DigitalSource Interface.
+ * The DigitalSource represents all the possible inputs for a counter or a
+ * quadrature encoder. The source may be
+ * either a digital input or an analog input. If the caller just provides a
+ * channel, then a digital input will be
+ * constructed and freed when finished for the source. The source can either be
+ * a digital input or analog trigger
+ * but not both.
+ */
+class DigitalSource : public InterruptableSensorBase {
+ public:
+  virtual ~DigitalSource() = default;
+  virtual HAL_Handle GetPortHandleForRouting() const = 0;
+  virtual AnalogTriggerType GetAnalogTriggerTypeForRouting() const = 0;
+  virtual bool IsAnalogTrigger() const = 0;
+  virtual int GetChannel() const = 0;
+};
+
+}  // namespace frc