ADD basic playlist support + youtube playlist support

playlist/PlayListInfoItem.java

@@ -0,0 +1,21 @@
+package org.schabi.newpipe.extractor.playlist;
+
+import org.schabi.newpipe.extractor.InfoItem;
+
+public class PlayListInfoItem implements InfoItem {
+
+    public int serviceId = -1;
+    public String name = "";
+    public String thumbnailUrl = "";
+    public String webPageUrl = "";
+
+    public InfoType infoType() {
+        return InfoType.PLAYLIST;
+    }
+    public String getTitle() {
+        return name;
+    }
+    public String getLink() {
+        return webPageUrl;
+    }
+}