Repackage CameraServer classes (#1321)

This is necessary for modularization.
Move the wpilibj CameraServer classes to the cameraserver package.
Move the edu.wpi.first.wpilibj.vision package to edu.wpi.first.vision.
To avoid code breakage, add deprecated copies of the wpilibj classes to the wpilibj jar.

cameraserver/src/main/java/edu/wpi/first/vision/VisionThread.java

@@ -0,0 +1,47 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2016-2018 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.vision;
+
+import edu.wpi.cscore.VideoSource;
+
+/**
+ * A vision thread is a special thread that runs a vision pipeline. It is a <i>daemon</i> thread;
+ * it does not prevent the program from exiting when all other non-daemon threads
+ * have finished running.
+ *
+ * @see VisionPipeline
+ * @see VisionRunner
+ * @see Thread#setDaemon(boolean)
+ */
+public class VisionThread extends Thread {
+  /**
+   * Creates a vision thread that continuously runs a {@link VisionPipeline}.
+   *
+   * @param visionRunner the runner for a vision pipeline
+   */
+  public VisionThread(VisionRunner<?> visionRunner) {
+    super(visionRunner::runForever, "WPILib Vision Thread");
+    setDaemon(true);
+  }
+
+  /**
+   * Creates a new vision thread that continuously runs the given vision pipeline. This is
+   * equivalent to {@code new VisionThread(new VisionRunner<>(videoSource, pipeline, listener))}.
+   *
+   * @param videoSource the source for images the pipeline should process
+   * @param pipeline    the pipeline to run
+   * @param listener    the listener to copy outputs from the pipeline after it runs
+   * @param <P>         the type of the pipeline
+   */
+  public <P extends VisionPipeline> VisionThread(VideoSource videoSource,
+                                                 P pipeline,
+                                                 VisionRunner.Listener<? super P> listener) {
+    this(new VisionRunner<>(videoSource, pipeline, listener));
+  }
+
+}