Added vscode task to generate launch.json

A few plugins will make the experience a lot better:
https://marketplace.visualstudio.com/items?itemName=redhat.java
https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-debug
https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack

src/main/java/net/fabricmc/loom/LoomGradlePlugin.java

@@ -37,6 +37,7 @@ public class LoomGradlePlugin extends AbstractPlugin {
 		makeTask("genSources", GenSourcesTask.class);
 
 		makeTask("genIdeaWorkspace", GenIdeaProjectTask.class).dependsOn("idea").setGroup("ide");
+		makeTask("vscode", GenVsCodeProjectTask.class).setGroup("ide");
 
 		makeTask("runClient", RunClientTask.class).dependsOn("buildNeeded").setGroup("minecraftMapped");
 		makeTask("runServer", RunServerTask.class).dependsOn("buildNeeded").setGroup("minecraftMapped");

src/main/java/net/fabricmc/loom/task/GenVsCodeProjectTask.java

@@ -0,0 +1,106 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.task;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.util.Constants;
+import net.fabricmc.loom.util.IdeaRunConfig;
+import org.apache.commons.io.FileUtils;
+import org.gradle.api.DefaultTask;
+import org.gradle.api.tasks.TaskAction;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+
+//Recommended vscode plugins:
+// https://marketplace.visualstudio.com/items?itemName=redhat.java
+// https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-debug
+// https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack
+public class GenVsCodeProjectTask extends DefaultTask {
+
+    @TaskAction
+    public void genRuns() {
+        LoomGradleExtension extension = getProject().getExtensions().getByType(LoomGradleExtension.class);
+        File projectDir = new File(".vscode");
+        if (!projectDir.exists()) {
+            projectDir.mkdir();
+        }
+        File launchJson = new File(projectDir, "launch.json");
+        if (launchJson.exists()) {
+            launchJson.delete();
+        }
+
+        VsCodeLaunch launch = new VsCodeLaunch();
+        launch.add(IdeaRunConfig.clientRunConfig(getProject()));
+        launch.add(IdeaRunConfig.serverRunConfig(getProject()));
+
+        Gson gson = new GsonBuilder().setPrettyPrinting().create();
+        String json = gson.toJson(launch);
+
+        try {
+            FileUtils.writeStringToFile(launchJson, json, StandardCharsets.UTF_8);
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to write launch.json", e);
+        }
+
+        File runDir = new File(Constants.WORKING_DIRECTORY, extension.runDir);
+        if (!runDir.exists()) {
+            runDir.mkdirs();
+        }
+    }
+
+    private static class VsCodeLaunch {
+        public String version = "0.2.0";
+        public List<VsCodeConfiguration> configurations = new ArrayList<>();
+
+        public void add(IdeaRunConfig runConfig) {
+            configurations.add(new VsCodeConfiguration(runConfig));
+        }
+    }
+
+    private static class VsCodeConfiguration {
+        public String type = "java";
+        public String name;
+        public String request = "launch";
+        public String cwd = "${workspaceFolder}\\run";
+        public String conolse = "internalConsole";
+        public boolean stopOnEntry = false;
+        public String mainClass;
+        public String vmArgs;
+        public String args;
+
+        public VsCodeConfiguration(IdeaRunConfig runConfig) {
+            this.name = runConfig.configName;
+            this.mainClass = runConfig.mainClass;
+            this.vmArgs = runConfig.vmArgs;
+            this.args = runConfig.programArgs;
+        }
+    }
+}